Part of this Range/Course duality (great on range, rough on course) comes largely from one reason: Time between shots. The range affords the ability to build a totally different kind of momentum. You can hit a shot every ten seconds on the range, but it takes you at least 4 minutes to hit your next shot out on the course.
You can get better!
1) When on the range, play a game. Design a par 4. Pretend it's 360. Hit whatever club you hit, measure distance, and see what you have left (you hit 200, you've got 160 in, hit your 160 club and see what happens!) The goal is to PRACTICE THE PACE OF COURSE PLAY. Yes, it takes a little longer when you switch clubs (perhaps you take a minute or two in between shots), but this gives you time to THINK. Remember that you are training your brain to tell the body what to do. Thinking about the way you are about to swing really helps!!
2) This one sounds a bit less fun (for me it sounds more fun) - double the amount of balls you hit in a week. The odds are good you can groove your swing much more to see an improved result on the course.
In high school, my buddies went out to play most days, and I would join them sometimes, but many times I'd hit an extra 2 buckets instead. I maintained my #1 position because of the confidence I had in my swing - a direct result of hitting so many more balls than my teammates! Iterations really matter!
I'm going to post my practice routine guidelines for the range soon.