I think you got it all wrong Golden. First, forget machines. Next, the arnold press just seems like a shoulder press with a lot of pointless twisty crap. You work the anterior good with shoulder press and lateral a bit too. You really need laterals or upright rows though.
As for posterior, I find they get worked enough with the back and don't need isolation. A set of rear delt rows can be added to your back routine if they need help though.
Upper fiber traps are in the shoulder area. They get some work with laterals, but shrugs are the best way to develop them.
The reason you can't get the entire shoulder area in 1 motion is because they are complex and involved in many different motions.
Arent upright rows bad for the shoulder joints? I was thinking aout starting doing them 2 weeks ago but i saw too many bad comments on it.
Many people have been saying military presses and shoulder presses work the lateral delts and make u wide so im starting to do them.