Wet vs. dry is roughly the equivalent of the sheepmen vs. the cattlemen. Do whatever gets you off. Dry inherently is the more secure method. With dry, when it's down it's down. With wet when it's down it's just sitting there until everything drys.
As far as window washers and squeegees, if you leave any sharp points and corners, even a 90 degree corner, that's where a squeegee will tend to snag the vinyl and start it to lift.
There's sound physics behind this phenomenon. When vinyl con\me to a sharp corner, outside corner for the more pedantic, there is necessarily a point where the vinyl is thicker that it is wide and there or thereabouts is where the minuscule amount of adhesive is incapable of holding the vinyl to the substrate.
On windows, vehicle doors, and most any other place where people might be squeegeeing, toweling, rubbing, etc. I fillet all outer corners to maybe a .01-.02 radius. There's various techniques for doing this depending on just what kind of software and object with which you're dealing. If you don't do it then you're just getting away with it and one day it will bite you.
