Yes, you can long line all year, but it will vary a bunch thru the summer and fall. Usually when trolling jigs slow and deep to the suspended fish is the trick. Once you locate them and find a school that is hungry you can clean up. If there are a bunch of white crappie around it seems that trolling crank baits works well on those fish during the summer. Pick up the speed for that. The guys on the MS thread have a lot of good info on how to do that, you should check them out too.