For me, it's all about trying to ensure a pleasant playing experience for everyone. Most times, that means being patient and letting the group ahead hole out. On my home course, East Roswell Park, I know pretty well how far my longest possible drive's going to go, so on a few holes, when a group is way beyond that (75-100 ft beyond it) and are already moving toward the basket (i.e., they've all thrown their approach shots), I will tee off if there's no possible way I can reach them, particularly if there are other groups coming up behind me. I would never throw if I thought that a reasonable person would have any question about my intentions, but keeping things flowing for everyone trumps slavish adherence to not teeing off until the previous group has holed out.
I'm also a nut about letting anyone who is even marginally likely to be playing faster than I am play through -- particularly the yahoos who I suspect will be throwing on top of me if I stay in front of them. I'd rather cool my heels on the next tee pad while they hole out the previous hole and then let them play through than have to be constantly looking over my shoulder.
Of course, I will in extreme circumstances deliberately take my time when someone acts like a jerk -- like the teenage sphincters who yelled "Fore" from the tee pad for Hole 2 at ERP when I was playing with a large group I was introducing to the sport. We had already let one group play through before that hole, and I held up our group when we got to the tee pad, expecting to let these four guys go ahead. They disappeared somewhere about that time, however, so I had our group go ahead. While we were all putting out, one of them stepped up to the tee pad, yelled "Fore", and acted like he was going to throw. I stood stock still over my disc for several seconds and stared back at them until one of them yelled "just kidding". I stayed there for several more seconds, had the rest of our group finish holing out, then took my sweet time lining up my putt. After I holed out, I stood there for several more seconds looking back at them before clearing my disc and walking to the next hole. They got some kind of message from it, as we never saw them behind us after that -- either they skipped to Hole 6, or gave up.