If it is a nice gun and you plan to own it for awhile, adjusting yourself to the gun doesn't make sense to me. When you buy a new car, do you adjust the seat, steering wheel and rear-view mirrors, or do you leave it like it was set in the factory? Except for the fortunate few who can buy a suit off the rack, most people pay to have a new suit tailored - why not a gun (which usually costs much more and you will likely own a lot longer than a suit?)
LOP is a little more flexible but drop and cast affect the gun's vertical and horizontal alignment relative to where you are looking. If I remember the calculation correctly, 1/4" castoff translates into a 30" change in R-L alignment at 40 yards, which is the difference between centering a target or hitting it with the edge of a full choke pattern. Why make the shooting game any harder by forcing yourself to adjust up/down/right/left everytime you pick up one of your guns?
Shoot the gun, check the fit, and have it altered as needed.
