A lot of it also has to do with driving environment and style.
My car now has 79k miles on it. All 4 rotors are still original. The front pads were changed at 48k miles and still have about 60% remaining. The back pads are the original ones, but will need a change in another 10k-15k miles.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record