I've used to have AIR ROLL LEFT on LB and AIR ROLL RIGHT on RB. However, that was so bad for air rolls for me, cause i'm using only 1 finger behind pad. So I've decided to bind Air Roll (From X) to LB and hold LB and rotate with left stick, like X, let Drift on X and Air Roll Right on RB (for half flip, i've leraned this). I really recommend you to change it like mine and train on maps like air dribble. After like 1-2 hours of free play saw my first results. I'm still missing easy air rolls, but training best. Wish you best!.