My understand is that the pad dust build up on disc which under high temperature will turn into a kind of coating. This coating is very hard so that it can actually protect the underlying metal disc from wear and consume the pad instead. However, this coating can detach from the disc surface piece by piece as it's mechanical bonded not chemical bonded. Consequently, the disc surface with this coating will wear slower than the area without this, which ultimately leads to uneven wear on the disc. To preserve (or to strip) the coating, I was told I should use the brake harder so that either the coating will be replenished, or it will be stripped more evenly before uneven wear starts to take place. I've been experimenting with this idea with the current set, and it survives much longer than previous disc (3 trackdays and thousands of miles on road so far), whereas previous sets usually failed BMW's test after one trackday and 1-2k mile on road.
Going forward as the car will soon out of warranty, I am thinking about trying yellow stuff with grooved disc (mainly to clear the brake pad dust from the surface, instead of improving cooling etc.). Drilled disc prone to crack and it won't offer much more (well, maybe slightly better ventilation, and slightly lighter) than grooved disc so I try to avoid them for now.