
Over the past year, I've been working with more people on different projects. In all cases, there is no boss. No deadlines other than what we set for ourselves. No standards other than what everyone involved agrees is best. Nothing is done until everyone says it's done.
Writing music is generally a very private activity. The ideas that form in your head usually marinate in there for a while, and you play with different possibilities each time you pick up your instrument or whenever you find yourself alone to think. By the time anyone else hears your new tune, you've probably spent 100+ hours on it. At least, that's how it usually works with me.
When collaborating, new ideas are immediately judged by whoever you're working with. You have to trust those people enough to be seen artistically naked. Either somebody likes your idea and starts to work with it, or your idea simply gets ignored. There's little room for ego, and a lot of room to take risks. The worst that can happen is your craziest idea just gets ignored.
Everyone I've worked with has a different style. Some people are meticulous with every note--it might work, but is it the best choice? Others work from their gut--if it feels right, it's right (and if it needs to change later, that's OK). Others come to the table knowing what they want and it's my job to first give them that, then start throwing curve balls until they realize what they really want is something else. Each approach is excellent as long as it's not closed off to new ideas.
I've learned a lot while collaborating with my friends. My ear has gotten better (ideas are usually spoken on the instrument, not by yelling out a chord). I've gotten a glimpse of how everyone else writes, and it helps get me out of jams while writing alone.
If you need to expand your creative palette, work with a friend.