I feel very lucky that my therapist is semi-retired, not too busy, working from home. What that means for me is that she is on time 95% of the time and always has time for sessions to run long without ever inconveniencing anyone which would bother me.

Personally, I don't mind occasional minimal lateness, though in the case I just read on another thread, client asked to come 30 minutes early, but then dr. wasn't available until 20 minutes late, now that would bother me.