SEO retainers usually cap your margins at 30% because you’re just selling...

https://wiki-zine.win/index.php/Testing_on_Client_Dime:_The_Ethics_of_the_Agency-as-Lab_Model

SEO retainers usually cap your margins at 30% because you’re just selling hours. If you start treating your agency like a lab to build your own internal tools, you can flip that model and get your margins north of 70%.