I use them when the water is rough and the fish are not shallow just because I can put some slack line out and let the cork ride the wave vs. being snatched. (When long poles are not needed)
But For me this only works if going with the wind so you must be able to control your boat speed. When trying to go into the wind.. The lines still get tight and start snatching
But...if the fish are shallow really no sense in it because to get rid of the bait snatching from the waves your having to give up the long pole length you're using because of the slack you put In Your lines....
As confusing as that sounds... That's my 2cents