20:1 is terrible. You may not have managers but other ICs then need to burden themselves with management duties. Even if you have 1:1 for half an hour every week, that’s 10 hours of just 1:1s. There is no reasonable way to keep track of it. It’s bad for the manager, it’s bad for the IC. Anything more than 10 is bad, ideal would be 7-8 reportees.
My manager has a bit more than 20 direct reports, and it works well in my experience. We have 1:1 every two weeks, but often there's not much to say.
The manager can manage that many people because he's not involved with our day-to-day work. We have a Scrum Master and Product Owner who handle their "management" parts. If there's some problem which needs manager's attention it's typically SM who communicates that.
The manager takes part in some meetings (like planning), but mostly just listening.
The difference is that they are not managing me, they "manage" their area of expertise. Better than an "all-rounder" who is doing PO, SM, HR, approving vacations and doing 1 on 1s ...
