The usual way to make the determination is to run a lubed, unresized case up into the die all the way and see if there is a crack of light between the die mouth and the shell holder when you do that. If there is, despite setting the die up with contact between them, the force of pushing the case up into the die has stretched the press frame by the height of that crack and you need to turn the die down that much further so it can't happen and cut the sizing operation short.
I have one press that will cam-over, an old Lyman Spar-T. The others all have stops on them that cause the rise of the ram to end before the handle linkage camming action raises it to its potential maximum. Thus, it can't quite cam up to, much less over that peak point (top dead center of the camming action). The stops are there because, in the process of the press linkage camming over the peak ram height position and having the ram start to descend on the other side the stroke, it passes through a point of infinite mechanical advantage, which too easily gives a person the strength to break the press frame if they have turned a die in too far.
The way the Lyman press works is the handle stops just past that point so that if you push the handle all the way and seen the ram drop just a tiny little bit, then screw a die mouth into finger-tight contact with it, when you reverse the stroke the slight upward travel of the ram before the handle is back in its main range of swing is the right amount of extra die compression to get a case all the way in and still have its mouth make contact with the shell holder. So, on that press, you can set the sizing die up just by feel and without looking for a crack of light, and as long as you always push the handle through the cam-over point during resizing, you will fully resize.
