6 hours was my longest.
The clubhouse booked my tee time right behind a tournament (didn't bother telling me about it either) and when our tee time arrived we had four foursomes yet to tee off. Every hole after that we had at least a 10min wait on the tee. I was playing the course for the first time and it really ruined it for me. The course itself is a tougher one and usually takes me just under 4 hours now.