Originally Posted by nhluhr

10 full turns is a HUGE amount of adjustment - far more than any inline adjuster I've ever seen even has available. You were probably just twisting the adjuster on the cable and not actually affecting anything at all. You will see the length of the inline adjuster physically change as you turn it. If you aren't seeing that, then you aren't making any change. Sometimes the ferrule slips on the adjuster and it doesn't do anything when you turn it. You'll have to 'hold it still' while turning it to get it to actually move.

With that said, from the issue you describe, assuming the derailleur is positioned properly AND the limits are adjusted properly, you should only have to turn the barrel about 2 full turns to fix your issue. I suspect though that you have more issues.