You can look at it that way. The gap is defined by the arbor bottoming out in the barrel assy. I prefer that being a solid and perm. fix. When getting the tol. that I want, you have to "over compensate " , ending up with a longer than needed arbor (just by a little). Then by taking off material from the front of the arbor, you arive at the desired gap. This allows the wedge key hole to elongate some ( .001-.002 at the most). Thats enough to allow the wedge to go in much further than the "like new" position. So, I close the front bearing space down with a big set screw. Its the arbor /barrel rationship that makes up the intended gap. If you pound a wedge in my set up, you can't close the gap. In a stock gun you will lock it up. Some of the Peiettas I've worked on actually have a long arbor and don't need the spacer. I give everyone the ability to keep the wedge in the position they want.
I have many customers that have fired 60, 70, 80 shots (They all will) with no binding whatsoever. This is because of the .002-.0025 gap that I set. If "stuff" can't get out , it can't get between the arbor and cyl. and cause it to bind. The bigger the gap, the more the crap!
Another reason for the close tol. is it allows for more precise tuning. The moving forward of the cyl. changes the timing /geometry and precision . As in any fine tuned device a tolerance has to be maintained and the closer they are, the longer the device will last.
Most of the open tops I've seen dont really have a defined gap, you can close them down and lock up the cyl. If it's too loose, it will damage the wedge and the key hole ( with each shot). That's why I prefer a tight fitting wedge as well. You shouldn't have to break down the gun and clean it while at the range. Breaking it down should be done when you're finished.