My bench, is really a work table, and it has a plywood top.
I usually take the ROS to it about once a year just to remove the glue and other stuff that gets on it. I also refresh the wax coating I put on it, helps (for a while) to keep things sort of clean...........
Here it is before I did anything to it, well besides make it a really dirty mess
I started with a #80 pad, and then went to a #120, not much point in going beyond that, I think
next I slathered on a thick coating of wax, basically put it on until I had a film of wax built up on the surface. At first the freshly sanded plywood sucks up the wax, but after a while it kind of builds up, at that point, I take a green scrubby pad (Scotch Brite?) and stick it on the ROS, I then go at it with this, it heats the wax up a bit and really pushes it into the wood.
After letting it dry, overnight, I take a buffing pad on the ROS to the table top, this takes only a few minutes, and the top, while not "Shinny" is a lot smoother and cleaner than before.
I know this is not "Fine Woodworking" but you CAN renew a plywood bench or table top to a working condtion, a few times at least.
Nice to have the bench all clean again!