The fatso can probably do 100s for sets of 15 easily and yet has nothing to show for it.
Using the chair with the back is really pointless if you want to work shoulders. They should toss them out of all gyms.
i dropped the backrest last shoulder workout after reading this thread, sat upright on a flat bench, and dropped the weight from the 80s i usually use to 60s.
I tried them both to parallel and below. (My parallel is actually about an inch below parallel, my elbows just barely drop below my shoulder, and my bicep/forearm angle is just barely less than 90*). Below was bringing the weight down to just above my clavicles.
I found that dropping the backrest DID make a sig improvement isolating the delt, i felt it much more.
However, going down below did absolutley nothing but cause me pain. I actually felt like it worked the delt LESS in my case than bringing it further down towards my shoulders