Agency retainers usually top out at 30 percent margins because you’re stuck...

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

Agency retainers usually top out at 30 percent margins because you’re stuck trading time for work. Build tools out of your internal workflows to hit 70 percent margins instead. Use your agency as a lab to create software that actually scales.