Never. I like to perch on the platform at the top of the ladder. When the water surface is still, I can see what I'm doing. Anybody in the water means I would be vacuuming blind. Besides, most of what I vacuum up is fine dirt and sand. When people are in the pool, it gets kicked up and takes hours to settle back out.
My hose is long enough, and suction strong enough, that popping the skimmer plate never occurred to me. In fact, I've tried to manually remove the skimmer plate with the pump running, and can't. My pole is long enough to reach the whole pool from the ladder, but I can't see it all due to glare, so I also walk around the outside.