The norm in my area is weekly. Twice weekly is unusual but not completely unheard of, and more than that seems very rare. I don't actually know anyone else in real life who does three or more sessions a week. Unless you count my therapist, who I believe sees his own therapist three or four times a week.

But then it's not like anyone I know (besides my partner) knows I go to therapy this often either. So for all I know I do know others, but none of us are talking about it.