Depends on the car and the driver and conditions. In WRC Loeb and some other drivers do not so much of LFB (of course they brake only with left foot but that's not what I mean). But some cars and surfaces need lots of LFB. I do LFB al the time on FWD cars but I don't feel I can make full use of it in AWD yet. In Cossie I LFB a little bit (especially to switch from one sideways corner to oanother it's efficent technique) but in Impreza rarely.