I needed to replace my pads on my M3 at 34,000km due to the top of the pad breaking off so to speak. Tons of auto x and and maybe two track days at full bore.
There was approximately 1/2 the pad left, but oddly started to lose pad at the top of it.
My GTS has 17,000km, only driven to the track and back (20+ full on track days, auto x,etc) and has far less than 1/2 pad left. Guess I’ll look at replacing them soon