Paul,
Statistically, we can group golfers into 6 or 7 basic tee shot lengths, i.e., (and rounded a bit) centered in 20-30 yard groups around about 150, 180, 216, 237, 258, and 290+ (forgetting those few supermen on the pro and college ranks) Given that the 290+ group makes up about 0.1% of players, those tees could be just big enough to stand on.
So, there is always the design decision of whether you want to use tee sets to design holes around those tee shot yardages to make the course most fun for everyone. (of course, there are many theories on what that actually means, as well) Most courses seem to like only 4 or 5 tees, and many use combo tees to get to the yardages their players prefer.