Good shoulder flexability, and proper hand spacing are two very important aspects to performing the presses.
As most everybody knows, I hold the opinion that shoulder, and chest work has been twisted in the modern world of training. While benching is a viable movement, Deltoids should be the primary upper body group to work.
Think about it from this aspect. What looks better?
Big chest small shoulders
Big shoulders small chest
I'll go with the latter. There is also the aspect of having good shoulder strenth and stabilty will lead to a big bench. No matter how you look at it. Proper shoulder work is the key to upper body mass, and strength. IMO!
Seated Behind-The-Neck Press - View Exercise
Lately, a few so-called certified trainers have given this exercise a bum rap. These are those freshly graduated, correspondence-course, all-knowing sages, as it were. Of course, no matter that Chuck Sipes, Bill Pearl, Reginald Park and Marvin Eder developed the strongest deltoids in natural training history just by doing behind-the-neck presses, the granddaddy of deltoid exercises. Once more, none on them developed debilitating shoulder dysfunction, as has been so tiresomely predicted.
For an entire era previous to Ronnie Coleman's out-of-this-galaxy musculature, behind-the-neck presses were to the 'man' as bench presses are today.