My initial thought is it's a dangerous idea, but the fact of the matter is most workbenches have a steel frame, and a thick wooden benchtop, so it's probably OK.
If you do this, I'd be careful about making sure the electrical outlets and anything you plan to work on are isolated from the metal frame of the bench. This includes where you're sitting when you're working. I'd make sure the plywood extends out over the frame in front of your sitting position so you aren't leaning up against the steel frame,
or that the legs of your chair don't contact the metal workbench frame.
I sat down at a workbench once that zapped me. Whoever owned the bench screwed an extending-arm worklamp
onto the metal frame. Somewhere, somehow, the lamp housing became electrically 'hot', and he never realized it.
I moved the chair up and leaned against the workbench frame in front of me, and however I was grounded, the metal
frame of the bench unexpected voltage used me to find ground. It took us a while to diagnose the problem.
All the other advice here is good too. ESD protection and etc, ... just my thoughts on avoiding becoming a ground
for the bench or your work on it.