I say " Don't get into a rut of not winning AND not having fun" just because ruts suck. I find it wonderfully refreshing teaching others how to play: I laugh more and I usually win.
For competitive-only, tournament playing, acrylic hunting X-wingers...I would suggest playing lists that beat you in a match- or lists that irritate you. You will see the other side, but ultimately you will have fun or get a better understanding of these lists.
MISSIONS are the best way to get out of a rut. Co-op, custom, home-made scenarios ROCK!, btw.