Ally,
Um, yeah, I'm sure, depending on site conditions and all, of course. And yes, I usually recommend five sets of tees, unless the back tee length is under 7000 yards. As courses stretch to 7600 yards, six sets would probably be better.
I have never hears supers complain about the budgets for tee maintenance, but we have actually been reducing and "fine tuning" tee sizes lately, and making them square just to make them most efficient use wise - i.e., build no more than you really need for purely artistic reasons, kind of like the old days.
Its simple math, really. If my goal is to allow the 135 yard hitter to theoretically get around the course in the same 36 strokes as others, then the maximum length is 135 x 36, or 4860 yards. Naturally, its quite a lot more fun if the second shot isn't always max length, so if we figure the average second shot at 100 yards, then a desired distance is 4230 yards, on normal ground, of course.
In reality, as we look at idividual holes and where hazards are, etc. it usually comes out in between. I also think most women and seniors who play these tees expect to not be able to reach every green in regulation, and in fact may score better when their approach shots come up just short of green side hazards and they get to use their short game to score. Every course is different, but I think fw tee players appreciate a course under 4800 yards, and of course, the "two tee sets" for women is becoming more popular, with the better players preferring to play from 54-5700 yards, about where the typical "senior tees" are located.