Agencies usually hit a ceiling at 30% margins because of all the manual labor....

https://www.bookmarking-presto.win/most-seo-retainers-cap-your-margins-at-30-percent-because-you-re-trapped-by

Agencies usually hit a ceiling at 30% margins because of all the manual labor. By treating your agency as a lab, you can turn those workflows into simple software and push margins past 70%. It is time to stop selling hours and start building assets.