Funnily enough, I get most of my Snappers on the drop.
If the plastic does reach the bottom, I will give it a few flicks and then let it rest for a little while, letting the rocking boat do the action. If still nothing, wind it up a bit then let it drop again.
Also as you probably know, a certain type/colour plastic which works one trip may not work the next so I like to keep trying different varieties until I do get a hit.