You honestly don't need that many. I play on PS4 now but when I was on PC, I would make sure 1-5 was the abilities I used all the time and 6-0 were less used abilities. For example, on my Scholar (healer) my main heals would be 1-5 with my DPS abilities 6-0. I'd have a hotbar directly above it using Shift as a modifier, and I'd use this hotbar for buffs, abilities with long cooldowns, that sort of thing. Again, the more used ones on the 1-5 slots. I'd only ever use 1-5 and Shift 1-5 with the keyboard, I'd usually click the rest. Honestly it is SO much easier on a controller, I have 32 abilities within such easy reach.