You can do whatever you want to auto's. LST is definitely great for them, and certain strains (particularity ones that flower early and finish in a short amount of time) don't respond as well to topping/supercropping/fimming, but the record holding Automazar plant was topped.. So that speaks for itself..
With that out of the way, what kind of lighting are you using? T5's definitely benefit from lst because you need the canopy all as close as possible to the bulbs.