I'm curious about the effect of wear on disc brake rotors.
-Has anyone ground a rotor down to the limit?
-Are there problems developing progressively or does failure strike without a warning?
-How many sets of pads (on average) can a rotor go through before it is used up?
There's always is a wear tolerance in the service instructions for cars and motorcycles. I don't know if this information can be obtained for bicycle brakes.
I apologize in advance if this subject has been discussed before but I haven't seen it come up in my searches. In fact most threads are about wear caused to wheels by rim brakes.