Should back wall have the plaster ground hole cut or fine as it is now?

[Daluu]

See photos, the contractors made openings for the screws that the trim will mount through I believe. But they didn't punch out the bigger hole of the plaster ground. But of course a solid surface (HI-MACS, like corian, 1/2" thick) will go over this as the finished wall. That one I figure should have the plaster ground sized hole cut.

So just checking whether they should have punched the bigger hole on the densshield back wall board.

I assume with this setup (no big hole in back wall), the end result the shower handle may stick out more than intended from reading https://terrylove.com/forums/index.php?threads/shower-handle-sticking-out-too-far.17565/. But also assume, even with hole, probably don't make difference, and that may affect the trim gasket installing tight against a back wall, in which case I guess the plaster ground would need to be kept rather than using the back wall as support.

I didn't take pic of the new installed Moen valve in the wall before the wall was put up, but I did have a pic of the old valve before it was replaced. It seems to me there's not much room to work with anyhow to moving the valve further recessed in the wall unless going into the other side of the wall if there's any much room left there.

On a different shower, with a Delta valve, they did cut opening in the back wall for the plaster ground. But that one's design might have been necessary to do? That one also will have solid surface (1/2") as the finished wall.

 

[Tuttles Revenge]

The valve normally comes with a "Plaster Guard" similar to the one pictured of the Delta valve. The guard is for the drywall / tile backer and tile to be cut up to and guarantee that the trim plate will cover and seal, and that you have access to replace the guts of the valve in the future.

It appears that you have a Moen Positemp rough in valve, which you need access to pull the protective sleeve out, which in turn allows access and keeps the pin/fork/keeper in place that holds the cartridge in place. As long as you can slide the keeper in and replace it, that valve doesn't need a lot of clearance. Some of them have isolation valves on the hot and cold inlets that you may want to verify are either present or not.. if not then no worry. If they are, then just a couple 1" circular holes would be adequate to gain access to them.