it's all about saving yor engine... after mod's to engine and tweek's in the gear changing (i have it changing when i want it) you don't want it labouring around the place or chopping between 3rd and 4th all the time. if i'm in town it won't go into 4th on light acceleration till i'm doing roughly 60kmh. if i'm not going to hit 60 for a while i leave it in 3rd which yes, also help's with braking. why wear out expensive pad's all day? if you want to know what work's best for you on the strip then there is only 1 way to find out mate.... get into it and get used to what work's best. changing up the gear's yourself will be best on the strip, you just gotta keep your eye on that rev counter so you change up before the rev limiter cut's in.