Hotbar 1, single target. 
Main raid bar. 

Hotbar 2, utility, buffs, repeats
Accessed via expanded controls
- Squeezing both triggers

Hotbar 3, mostly repeat of bar 1, but it's for aoe
Rarely used in raid scenario. 
Generally you need to aoe or you need to single target. 
Use bar 1 or 3 depending on that scenario
Nvr need to aoe and single target at the same time . 
So no need to have aoe skills and single target skills same time. 
Changing hotbar from 1 to 3 or 3 to 1... it's not hard anyway.

wanhope_despair