What Small SEO Fix Had the Biggest Impact on Your Organic Traffic?

I've realized that SEO isn't usually about one huge breakthrough—it's often a collection of small improvements that compound over time.

For me, a few changes made a noticeable difference:

Improving page speed and Core Web Vitals.
Refreshing old content instead of only publishing new articles.
Writing more helpful, user-focused content rather than chasing keyword density.
Adding internal links between related articles.
Optimizing titles and meta descriptions to improve CTR.

I'm curious about other founders and builders:

What's one SEO change that produced surprisingly good results for your website or SaaS?

Was it technical SEO, content updates, backlinks, programmatic SEO, AI-assisted content, or something completely unexpected?

I'd love to hear real-world experiences and lessons learned.