I am in an automatic and I do the same thing as ctuna... no brakes above 20-15 most of the time. I don't believe it's much wear on the engine or tranny, usually under 4k like the man says and really cuts down on the brake wear... plus it's 100x more fun!
'08 E90 328xi, PlatBr, ZPP, ZCW
Winter: Dunlop Winter Sport M3 on OEM Style 268s.
Now: Conti ExtremeContact DW on VMR V710s, 245/35/18x8.5 square.
Matte black grilles and blacklines installed.
Euro Bixenons, AFE CAI, BMW PE, AA tune coming soon.