I think a lot of it is individual. I had no shoulder issues whatsoever- never have had any shoulder problems other than very minor cuff tweaks from going too heavy on upright rows.
One thing that I think helps me in terms of shoulder health is that I have always used some sort of a heavy rowing movement along with pressing and the two are close as far as weight goes. At the end of my first 5x5 run I tripled 315 on bench and 300 on parallel bb rows. Being nearly as strong in the row means that I'm able to control and balance my bench press weight without undue stress on my shoulders. Also, overhead pressing serves this purpose- it strengthens the cuffs themselves as well.
Of course if you have previous injuries then I don't know what to tell you. I'm just guessing as to why I've never had trouble despite the rather common occurance of injury to those who are frequent benchers.
EDIT: Got carried away and didn't answer your q

. I did all my movements pronated.
Also, I'd bench flat as you can apply more load that way, unless you have an injury already.