How to diagnose and fix the biggest blocker to PPC growth

We’ve all been there. A client wants to scale their Google Ads account from €10,000 per month to €100,000. So, you do what any good PPC manager would do:

• Refine your bidding strategy.
• Test new ad copy variations.
• Expand your keyword portfolio.
• Optimize landing pages.
• Improve Quality Scores.
• Launch Performance Max campaigns.

Three months later, you’ve increased ad spend by 15%. The client is… fine with it. But you know you should be doing better.

Here’s the uncomfortable truth: Most pay-per-click (PPC) optimization work is sophisticated procrastination.

What the theory of constraints teaches us about PPC

The theory of constraints, developed by Eliyahu Goldratt for manufacturing systems, reveals something counterintuitive. Every system is limited by exactly one bottleneck at any given time.

Making your marketing team twice as efficient won’t help if production capacity is the constraint. Similarly, improving your ad copy click-through rate (CTR) by 20% won’t move the needle if your real constraint is budget approval or landing page conversion rate.

The theory demands radical focus. Identify the single weakest link and treat everything else as less important.

Applied to PPC, this means: Stop optimizing everything. Find your number one constraint. Fix only that and then move on.

7 constraints that prevent PPC scaling

In my years of managing PPC accounts, I’ve found that almost every scaling challenge falls into one of seven categories:

1. Budget

Signal: You could profitably spend more, but you’re capped by client approval.

Example: Your campaigns are profitable at €10,000 per month with room to spend €50,000, but your client won’t approve the additional budget. Sometimes it’s risk aversion, but other times it’s a cash flow issue. 

The fix: Build a business case demonstrating profitability with a higher spend. Show historical return on ad spend (ROAS), competitive benchmarks, and projected returns.

What to ignore: Avoid ad copy testing, keyword expansion, bidding optimization, and new campaigns. None of this matters if you can’t spend more money anyway.

Dig deeper: PPC campaign budgeting and bidding strategies

2. Impression share

Signal: You’re already capturing 90%+ impression share and can’t buy more traffic.

Example: You’re targeting a niche B2B market with only 1,000 relevant searches per month.

The fix: Expand to related keywords or use broader match types. Alternatively, enter new geographic markets or add complementary platforms like Microsoft Ads or LinkedIn Ads.

What to ignore: Don’t worry about bidding optimization, since you’re already buying almost all available impressions.

3. Creative

Signal: You have high impression share but low CTRs, resulting in a premium cost per click (CPC).

Example: You’re showing ads on 80% of searches, but CTR is 2% when the industry average is 5%.

The fix: Aggressively test ad copy, better message-market fit, and more compelling.

What to ignore: Avoid keyword expansion. Your ads are already visible, they just aren’t getting clicks.

4. Conversion rate

Signal: You’re generating strong traffic volume and acceptable CPC, but terrible conversion rates.

Example: You’re getting 10,000 clicks per month. But you have a 1% conversion rate when you should be getting 5%+.

The fix: Optimize landing pages, improve offers, and refine sales funnels.

What to ignore: Don’t launch more traffic campaigns. You’re already wasting the traffic you have.

5. Fulfillment

Signal: Your campaigns could generate more leads. But the client’s sales or operations team can’t handle more.

Example: You’re generating 500 leads per month, but sales can only process 100.

The fix: This is a client operations issue, not a PPC issue. Help them identify it, but know that the solution lies outside your control. Do more business consulting for your client while maintaining the current PPC level.

What to ignore: Pause all PPC optimization, as the system can’t absorb more volume.

6. Profitability

Signal: You can scale volume, but cost per acquisition (CPA) is too high to be profitable.

Example: You need €50 CPA to break even, but you’re currently at €80 CPA.

The fix: Improve unit economics through better targeting or creative optimization. Alternatively, help the client rethink their pricing or improve customer lifetime value (LTV).

What to ignore: Set aside volume tactics until the economics work at the current scale.

7. Tracking or attribution

Signal: Attribution is broken, so you can’t confidently scale the campaign.

Example: You’re seeing complex multi-touch customer journeys where you can’t definitively prove PPC’s contribution.

The fix: Implement better tracking and test different tracking stacks (e.g., server-side, fingerprinting, or cookie-based). You can also update your attribution modeling or develop first-party data capabilities.

What to ignore: Avoid scaling any channel until you know what actually drives results.

Dig deeper: How to track and measure PPC campaigns

The diagnostic framework

Identifying your constraint requires methodical analysis rather than gut feeling. Here’s how to uncover what’s holding your account back.

Run an audit

Start by benchmarking critical metrics:

• Impression share: If you’re capturing less than 50% of available impressions, your constraint is likely budget or bids preventing you from competing effectively.
• CTR: Performance below industry benchmarks signals a creative constraint where your messaging isn’t resonating with searchers.
• CPC: Unusually high CPCs often indicate a Quality Score constraint, which reflects poor ad relevance or landing page experience.
• Conversion rate: If this metric lags compared to historical performance or industry standards, your constraint is the landing page.
• Search volume: If you’ve already captured the majority of relevant searches, your constraint is inventory exhaustion.

Don’t overlook operational metrics either. Check fulfillment capacity by determining how many leads your client’s team can handle per month.

Finally, document your approved budget against what you could profitably spend. If there’s a sizable difference, budget approval is your primary constraint.

Ask the critical question

With your audit complete, resist the temptation to create a prioritized list. Instead, force yourself to answer one question: “If I could only fix one of these metrics, which would unlock 10x growth?”

That single metric is your constraint. Everything else, regardless of how suboptimal it appears, is secondary until you’ve broken through this bottleneck.

Apply radical focus

Once you’ve identified your primary constraint, it’s time to change your entire approach. This is where marketers tend to fail. They acknowledge the constraint but continue hedging their efforts across multiple fronts.

Why constraints are dynamic (and why that’s good)

Understanding constraint theory means recognizing that bottlenecks shift as you scale.

Consider a typical scaling journey. In month one, you’re stuck at a €10,000 monthly budget despite profitable performance metrics.

Your constraint is budget, so leadership won’t approve more ad spend. You build the business case, secure approval, and immediately scale to €30,000 monthly spend.

Success, right? Not quite. You’ve just revealed the next constraint.

By month two, you’re capturing 95% of core keyword inventory. Your new constraint is impression share, as you’ve exhausted available traffic in your primary audience.

The fix is to expand to related terms and broader match types to bring new searchers into your funnel. This expansion takes you to €50,000 per month.

Month three presents a new challenge. Your expanded traffic converts at 2% while your original core traffic maintains 5% conversion rates. Your constraint has shifted to conversion rate.

The broader audience needs different messaging or a modified landing page experience. So, you focus exclusively on improving the post-click experience until conversion rate recovers to 4%. This lets you scale to €80,000 per month.

By month four, your sales team is drowning in 500 leads per month, which more than they can effectively manage. Your constraint shifts from the PPC account to fulfillment capacity. The client hires additional sales staff to handle volume, and you scale to €120,000 per month.

Each new constraint is proof you’ve graduated to the next level. Many accounts never experience the problem of fulfillment constraints because they never break through the earlier barriers of budget and inventory.

Common traps to avoid when scaling PPC

The ‘optimize everything’ approach

When you try to optimize everything, you might spend:

• 10 hours optimizing ad copy (+0.2% CTR)
• 10 hours improving landing page (+0.5% CVR)
• 10 hours refining bid strategy (+3% efficiency)

After investing 30 hours, you only achieve 5% account growth.

Instead, identify the primary constraint (e.g., conversion rate).Then, invest all 30 hours in landing page optimization. Continue to monitor your conversion rate.

Shiny object syndrome

Say your budget is capped by the client at €10,000 by client. But you spend 20 hours testing Performance Max because it’s new and interesting.

After running those tests, you achieve zero scale. And your budget is still capped at €10,000.

Instead, recognize that your primary constraint is budget approval. Build a business case, secure approval, and start scaling immediately.

Analysis paralysis

If you wait for perfect Google Analytics 4 tracking before scaling,  competitors may move forward with good enough attribution.

This can mean losing six months with no scale.

Aim for 80% accurate tracking. Perfect attribution is rarely the actual constraint.

How to implement the theory of constraints in your agency or in-house team

For your next client strategy call

Don’t say: “We’ll optimize your campaigns across multiple dimensions, bidding, creative, targeting, and see what drives the best results.”

Instead, say this: “Before we optimize anything, I need to diagnose your constraint. Once I identify it, I’ll focus exclusively on fixing that bottleneck while maintaining everything else. When it’s resolved, we’ll tackle the next constraint. This is how we’ll reach your goals.”

For your team

Implement a Constraint Monday ritual. Every Monday, each account manager identifies the primary constraint for their top three accounts. The team focuses the week’s efforts on moving those specific constraints.

On Friday, review the results. Did the constraint move?

• If yes, what’s the new constraint?
• If not, you had the wrong diagnosis. Try again.

From tactical to strategic PPC scaling

The difference between a good PPC manager and a great one isn’t technical skill. Instead, it’s the ability to identify constraints.

Good PPC managers optimize everything and achieve incremental gains. Great PPC managers identify the one thing preventing scale and fix only that, achieving exponential gains.

When you master the theory of constraints, you stop being seen as a tactical campaign manager and start being recognized as a strategic growth partner.

You’re no longer reporting on CTR improvements and Quality Score gains. You’re diagnosing business constraints and unlocking growth that seemed impossible.

That’s the shift that transforms PPC careers and accounts.