Since your symptoms seem to vary, I assume you haven't "devolved" into some bad form habit(been there,done that, own the T-shirt concession). I've gone through periods where I shot alot and my shafts seemed weaker. Most of the time I'll find I've inadvertently lengthened my draw. I thinking this is due to engaging the back muscles thing and "expanding" my draw, without changing anchor. I'm usually unaware of it until I get somebody to measure it. We're not talking a huge amount, but enough that I may have to drop point weight to get bare shafts flying right agian.