Never used one as a leave behind gill net... Have used a seine net to catch fish for live bait... It is more of an active thing and they do well...

With active use, you want to "herd" the fish into a place they can't get to, then scoop up and out.

With the hand and leave, you just let the fish get tangled on their own accord. Once again, mesh size is the key to these two functions. Hard to try the leave method as it is illegal unless in a survival situation.