if you wait until drywall to terminate and do a 1st test, why not wait a little longer and go ahead and do the final trim and test? I will put the plates and/or keystones in a baggie at the wall to protect from paint. At the head-end, for a structured wiring can, it is the final termination. If its a rack, I ask the GC / painter to finish my closet. I may go on and put the rack in the project and leave it empty and cover it, or just leave the patch panel there in a garbage bag. It depends on how many drops are involved.