A fortnightly 30min calendar event is about right, and even then sometimes we skip it because there's nothing to talk about. That's the point, it's there if we need it.
I think this is it, an hour a week can be too much in some cases, but never having 1-on-1s can lead to some things deteriorating, depending on the manager. Otherwise trivial issues accumulate and become non-trivial, both sides can get out of the loop etc.