Most SEO retainers trap you at 30 percent margins because you’re selling time....

https://dibz.me/blog/why-a-handful-of-european-seo-agencies-stopped-being-agencies-and-1138

Most SEO retainers trap you at 30 percent margins because you’re selling time. By turning your internal workflows into a simple software product, you can push past 70 percent margins. Build a lab instead of just another agency.