I caught 3 crappie this weekend in a matter of minutes on a straight bank with no structure in the creek. Then didnt catch another fish the rest of the afternoon. Crappie school up together and you can usually slay them when you find them, the trick is finding them. Also when I hammer the fish real fast I think it helps if you think you found a school to take it easy or they'll scatter. Catch 1 fish and wait a minute or two before tossing your jig back down, catching them back to back seems to scatter them out making it harder to keep them biting but thats just me.

Also if the water is cold like it is now the best advice is to keep that jig moving SLOW the cold water slows metabolism and fish move slower so you'll need to move your jig slower. Reel real slow and as the water warms up you can start moving it faster