How many times can I use rubbing compound?

[termigator]

My wife has a 2000 Naples Gold Honda Accord. It's her daily driver and has never seen the inside of a garage for more than two days in a row. It had some pretty strong water spot etchings in the surface which I have been able to reduce but not rid completely. I have used the regular Turtle Wax rubbing compound once by hand and 3M's Medium Cut compound once or twice with a PC and then 3M's Fine Cut compound about three times with a PC.
My question is: How many times can I use rubbing compound (the 3M Medium to be more precise. The TW by hand was a PITA!) before the clearcoat get's damaged? I was going to try the Medium Cut with a yellow PC pad instead of the orange pad one I've been using to get more cut.