I audited a website last month that was getting 50,000 organic visitors a month and growing 20% month-over-month. Within two months, the growth flatlined. No algorithm update. No competitor activity. Just a technical SEO mistake that went unnoticed for six weeks.
This happens more often than you'd think. Growing websites are complex. Development teams are moving fast. SEO isn't always top of mind when you're focused on building new features. But three technical SEO mistakes keep appearing in my audits, and each one is quietly destroying search visibility for otherwise good websites.
Mistake #1: Indexation Death by Robots.txt
Here's the scenario: You're adding a new section to your website. Staging environment, development environment, production environment. Your development team creates a robots.txt file on the staging and development servers that blocks search engines. This is correct. You don't want Google crawling your unfinished staging site.
Then they push to production. They forget to update the robots.txt. Now Google can't index your new section. Or worse, they can't index your entire new site.
I found this at a SaaS company that just replatformed. Their old site was fine. Their new site was live. But the robots.txt was still set to block all crawlers. It took three weeks before anyone noticed because the site was new—they didn't have historical organic traffic to compare against. They were expecting organic growth and wondering why it wasn't happening.
The fix took two minutes. The damage took two months to repair because Google had to re-crawl everything.
Action: Audit your robots.txt every time you deploy to production. Specifically check for:
- User-agent: * Disallow: / (blocks everything)
- Blocks on /admin, /staging, or other sensitive paths that shouldn't be public
- Any rules that block your actual site content
Use Google Search Console to verify that Google can crawl your key pages.
Mistake #2: Pagination Destroying Crawl Budget
You have a blog with 500 published posts. You set up pagination: /blog/page/1, /blog/page/2, /blog/page/500. Google has to crawl all 500 pages to find all your content. That's crawl budget spent on pages that don't contain unique content, just links to your posts.
On a large site, this is a massive waste. Google crawls a limited number of pages per day on your domain (your "crawl budget"). If you're wasting crawl budget on pagination pages, Google crawls fewer of your actual posts.
I audited an e-commerce site with 10,000 products across multiple categories with pagination. Google was spending 40% of its crawl budget on pagination pages. They had 6,000 products that Google wasn't crawling at all because it ran out of crawl budget.
Here's what I found: The pagination pages were getting indexed in Google Search Console. They weren't driving any traffic. They weren't ranking for anything. They were just consuming crawl budget.
Action: Use rel="next" and rel="prev" tags to tell Google that pagination pages are related but not independent. Better: use infinite scroll or load-more buttons instead of pagination. Even better: use URL parameters (like ?page=2) and disallow those URLs in robots.txt, then use rel="canonical" to point to the main page.
For e-commerce specifically: Prioritize crawling product pages over category pagination. Tell Google which pages matter.
Mistake #3: Site Speed Decay During Growth
Your website is fast. You get a 95 on PageSpeed Insights. Then you add more features. More tracking pixels. More third-party scripts. More ads. Every feature is small. Each one adds 50 milliseconds. After ten features, you're at 3 seconds. After twenty, you're at 5 seconds. And somehow nobody noticed because it was gradual.
A news website I audited went from a 2-second load time to a 5-second load time over six months. No single change was catastrophic. It was death by a thousand cuts: a new ad network, a new analytics tool, a new personalization engine, a new recommendations widget, updated fonts, updated images. Each was small. Together, they slowed the site to a crawl.
Google's Core Web Vitals now directly impact ranking. Slow sites rank lower. But more importantly for these growing websites: slow sites get crawled less frequently. Google reduces crawl frequency on slow sites to save resources. Which means new content takes longer to get indexed.
The news site was publishing 50 new articles a day. Because the site was slow, Google was only crawling it once a day instead of once an hour. New articles took 24 hours to get indexed. By then, they were already stale news.
Action: Set up regular PageSpeed Insights monitoring. Run audits weekly, not just once. Track the trend, not just the current score. When you add a new script or widget, measure the performance impact before deployment. Set a performance budget—"new features can't add more than 100ms to load time."
Audit your third-party scripts. Are you using five analytics tools when one would suffice? Are you loading ad networks on every page? Are you lazy-loading images or does every image load on page load?
A Word on Technical Debt
These mistakes aren't failures of knowledge. Every competent developer knows about robots.txt, crawl budget, and page speed. The mistake is thinking SEO is something you "fix" once and then don't worry about. Technical SEO is maintenance. It's things that decay over time as you add features and grow.
The websites that maintain organic growth are the ones that treat technical SEO as an ongoing responsibility. Not a quarterly audit. Ongoing monitoring and maintenance.
If you're managing a growing website: Audit your technical SEO now. Then audit it again in two months. Then set up monthly monitoring. Find the technical problems before they cost you traffic.
Most of the websites I audit are doing 80% of things right. They're just missing the 20% that matters. And by the time they notice, they've already lost months of organic growth.
Don't be that website.