I've never tried any more than two passes - WTG and ATG - adaptive to the direction of the grain, of course. If I feel like a really smooth shave I'll do two passes. Most days for work purposes I'll only do one pass WTG. I'm not sure my face could handle three passes...

I shave my head too (every second day, lately). Early on I tried additional ATG passes. Tricky, particularly at the back where you can't see the blade directly - you need some extreme holds and flexible shoulders and wrists for that one... Anyhoo, I found that there's not much to be gained doing that (except an unintentional scalping!) in terms of smoothness, and I felt there was little return for the added effort, given you just need to do it again in a couple of days.

Anyway, I guess my point (there's a point??) is that I feel if you're cleanly shaved, and people aren't going to be stroking your face (or head) throughout the day, a single or max 2 pass shave is OK. (I *do* get people wanting to stroke my head throughout the day, or is that smack it...? - but maybe that's just me ... )

James.