I've decided it's a lot like learning to drive stick. When I started driving stick, it was a real ordeal to shift, and I'd only do it when absolutely necessary. Now, I shift constantly, because it's not this huge stressful event anymore -- it's just part of driving, like using the turn signal or hitting the gas.

I've noticed that I shift a lot more on my bike than I used to, but I'm still hesitant to shift unless I think it's "absolutely necessary." I'm sure that in time, I'll be more willing to shift in situations where it'll give me a small boost.