All of my three brothers play guitar to varying degrees. Although we've never all got together in the same band we have stood in for one-another on occassion. It was the best learning tool ever! I am currently teaching a guy "in a vaccuum" and it's such hard work sometimes. He has great tenacity and wants me to tab everything I know for him, but can miss out a note or two when playing a piece and not notice that his timings out as a result! That sort of musical instinct only comes from playing along with others.