SEO has an image problem. Businesses invest in it for 3 months, see modest results, get impatient, stop — and then conclude that "SEO doesn't work." Then they try it again when business gets slow, stop when things pick up, and repeat the cycle indefinitely.
This stop-and-start pattern is precisely why most businesses never see the full value of SEO. Understanding why requires understanding how SEO actually works — and what it has in common with compound interest.
SEO Is Not a Campaign. It's Infrastructure.
When you run a Google Ads campaign, you pay for traffic and the moment you stop paying, the traffic stops. It's transactional. Predictable. Instant — and impermanent.
SEO works differently. When you invest in building a properly optimised website, earning quality backlinks, publishing useful content, and accumulating genuine reviews, you're building an asset. Each improvement compounds on the last.
- A new page ranks for a keyword → earns traffic → earns links → ranks higher → earns more traffic
- A new review improves your average rating → improves your local ranking → more impressions → more reviews
- A well-written article earns a backlink → strengthens domain authority → improves ranking for other pages
This flywheel takes time to spin up. But once it's moving, the cost of maintaining momentum is far lower than the cost of building it again from scratch.
The Real Cost of Stopping
What happens when you stop your SEO activity? Not immediately — but over time:
- Your competitors, who kept going, slowly overtake your rankings
- Your content becomes outdated and Google deprioritises it
- Your review velocity drops, weakening your local ranking
- Your domain authority stagnates while others grow
By the time you notice the decline and restart your efforts, you've lost 6–12 months of compounded progress. You're not just back to square one — you're often behind where you started, because your competitors have moved forward.
This is why agencies talk about SEO as a long-term engagement. It's not because they want to lock you in — it's because the structure of how SEO works rewards consistency above all else.
How to Calculate the ROI of SEO
The ROI of SEO is harder to calculate than paid advertising — but it's also far more impressive when measured over the right time horizon. Here's a simple framework:
Step 1: Calculate the value of a customer. What's the average lifetime value of a new client for your business? A plumber might get DKK 15,000 from a customer over 3 years. A therapist might get DKK 30,000 from a long-term client.
Step 2: Estimate monthly leads from organic search. How many enquiries per month do you get from Google? If you're not tracking this, Google Analytics and Google Search Console (both free) will tell you.
Step 3: Apply your conversion rate. If 20% of organic visitors who contact you become clients, and you get 10 organic enquiries per month, that's 2 new clients per month from SEO.
Step 4: Multiply by customer lifetime value. 2 new clients × DKK 15,000 LTV = DKK 30,000 per month in revenue attributable to organic SEO.
Compare that against what SEO costs — whether you're paying an agency or investing time — and the math is almost always compelling.
SEO vs Paid Ads: The Right Balance
Paid ads and SEO aren't enemies. The most effective digital marketing strategies use both:
- Paid ads for immediate results, testing new services, or filling gaps during quiet periods
- SEO for building long-term, owned traffic that generates leads without ongoing cost
The mistake is treating them as alternatives rather than complements. The businesses that over-rely on paid ads are permanently dependent on spending to generate enquiries. The businesses that invest in SEO build an asset that continues to generate return long after the initial investment is complete.
Consistency Is the Strategy
You don't need to publish 10 articles a month or rebuild your website every year. The most sustainable SEO strategy for a small business is simple:
- One new piece of quality content per month
- Regular Google Business Profile updates and post activity
- A systematic approach to asking for reviews
- A website that's technically sound and updated when needed
Do those four things consistently for 12 months and you'll have an organic presence that most of your competitors haven't managed to build in years. Stop, start, stop, start — and you'll spend the same money with a fraction of the results.