Good question! I think there’s probably more to this story, but personally, I can play with all amounts of overlap and I’ve noticed no correlation between that and my ability to execute picking motions. We even put a chapter in the Primer about this, if only to demonstrate that all the combinations sort of work, even if there may difference we haven’t yet picked up on:
David Grier is an interesting case because he actually uses negative overlap, where the pick sticks our farther than the thumb. I’ve tried this and it seems to work. I spoke to David about this specifically when he came back over the summer, just to make sure I was copying him accurately. It feels odd because it’s not what I normally do. But it does work, and if I made myself do it all the time I’m sure it would become more familiar in feel.
If you’re saying the amount of overlap you’re using actually changes while you’re playing, I would suggest this is something you’ve learned to do, and are doing deliberately, at some level, even if it feels automatic or unavoidable.
One thing you can try is deliberately attempting different grips, even ones you don’t intend to use long-term. This can be a real eye-opener. Middle finger and three-finger grips are particularly interesting because they’re so different and require a change in arm position and a change in picking motion, to an approach more like Albert Lee or Eddie Van Halen. Again, you don’t have to intend to play this way long term. The idea is that by trying the different thing and attempting to get good at it, you may learn something more general about grip and motion (either consciously or subconsciously) that you then use to become more aware and/or comfortable in all the other grips and motions you know. Conversely, if you constantly bang away on the same thing, without trying anything new, you’re not giving your hands much new information to learn from.
And who knows, some of the other grips might turn out to be interesting to you and you might keep them in the rotation and use them for certain things. I know I’ve been surprised that way many times.
