What with the price of spares versus the price of fuel at the pumps these days, replacing consumables like brake pads/discs, oil and filters is an almost insignificant cost anyway.
I just replaced discs and pads and the old pads still had over 1/2" left on them. It would cost over £5000 in diesel before I would need to replace the pads again, at £16. Can't imagine running them down to the metal.
I don't know what my point was, but that's my two pence worth...