Retainers are a treadmill that usually caps your agency at 30 percent margins....

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

Retainers are a treadmill that usually caps your agency at 30 percent margins. By turning your internal workflows into software, you can hit 70 percent margins and build real equity. Treat your agency like a lab to build your own product.