I changed my brakes for the first time at 65k I went OEM again since they lasted that long (pads and rotors). Two weeks ago did the front pads at 104k OEM again still had plenty of pad on the old ones . Brought on ebay.
I have had rotors last me a very very long time as long as you take care of them and check the pads. If you keep a watchful eye on the pad material amounts then you should never destroy a rotor by letting the pad material run out.
Rotors will become too thin and warp at some point though.
BTW still on the original rotors at 65K miles. pads have changed a few times.
when you change your pads pull the rotor off as well.
-clean with brake clean and a brass brush the mating surface on the hub and rotor
-knock off loose rust
-check the lubrication of the caliper slides. you should be able to pull on the caliper before loosening any nuts/bolts and with your own strength be able to compress the caliper. it should move back and forth on the slides without any binding.
- do a total rebuild of the calipers at 45K miles intervals. at least flush out the slides with brake clean and rags. re-grease and install new boots.
doing all of that helps rotors wear evenly and consistently.