You did 3-4 years with dozens. I am at 20 years and more complexity. For a number of years, I managed staff and interns - just keeping interns busy chews up a lot of time. I had a co-founder to start with, and was then solo running it from then. Once you have staff but not the scale to get help managing that, it gets seriously difficult. When I started, things like Toggl didn't really exist. I used to print out and manually sum hours from staff per client/project and per month. And then create dozens of invoices each month manually in MYOB, an awful and miserable interface. It was a huge timesink. I couldn't outsource it because I was the only one with true knowledge of each relationship - what to bill in what way, which clients were sensitive, etc.

I'm not saying it's impossible to do it OK, I'm saying it's easy to get it wrong and fall behind. I mentioned the idea of an opinionated business framework to a friend (freelancing very occasionally 1-2 years) and they said "Oh YES, absolutely." And that's for someone who'd send 2-3 invoices a month, not 50+.

It's not just about missing invoices. Freelancing didn't really satisfy me to be a one man business army. Having dozens of active clients sounds like a horror movie to me. I also worried much more as a freelancer than as an employee.

It's great that you could do it.