When longlining works best is when the crappie are on the move. And that's usually early spring until early summer and late fall into cold winter. That's usually when the fish are moving from deep waters into more shallower waters chasing bait and that's where the 1/16th and smaller jigs come into play. Depending on your personal LLing setup tells which weight jig to use. 1/32nd jigs are generally used to fish 5' deep or so and the 1/16ths can get you down to around 8' deep. Now is where you use variables such as adding splitshots or double jig rigging or even moving up to heavier jigs such as the 1/8ths to get even deeper. As far as the 1/4th jigheads.....I've never used 'em. I could only guess that with my setup they'd run 20'-25' deep and when crappie are that deep usually they aint chasing jigs all that much IMO. If I were still chasing the crappie then (hot summer months) I'd probably switch over to spider rigging using meat under my rods.