[Si Coe]

The only reason I can think of for doggedly sticking to one brand is compatibility. This can take many levels from using the same parts down to more basic stuff as using imperial/metric screws. Associated drivers often have both a B/C4.1 and a B44 because they need imperial tools for both.

However, in 2013 most cars are metric, and aside from stuff like shock bodies etc most cars share very few parts. So there is little reason to stick with the same brand - if you do its normally because you like how their cars work. If you don't you need to move brands!