I would take the view that holding a top lever whilst closing the gun will accelerate wear - not delay it.

Reason being if the top lever is not allowed to snap back shut, then the gun may not have locked properly, and tiny amounts of movement may take place when the gun is fired thus causing accelerated wear.

If the lever is not allowed to snap back into place, how can it be seated properly - it can't, the spring and "wedge shape" of the bolt(or conical if a Beretta) bearing down on the lumps is there for a purpose to ensure a solid "tapered" lock up. Holding and allowing the top lever to just go back into place prevents this preocess happening.

Each to their own, you make your choice, I know what mine would be.

Jonty