I don't plan on doing any hardcore content like Alex Savage on my AST... but what the OP talks about is kind of the direction I've been shifting towards.

There have been a few times where a DPS (mostly often BRDs) will kindly request that I give them Spears or Arrows when I can, so I happily take on their request (I'm probably sympathetic because my main is BRD). And of course, Spire if someone desperately needs/asks for it. (Can't wait until SE implements that TP bar option!) I also typically try to not give Spear to tanks unless they specifically ask for it, because a tank in my FC told me to never give it to him. I think it screws up his rotation or something. Probably a muscle memory/reflex thing for him.

But aside from those special cases? Bole for tanks, Balance for DPS, everything else for myself -- as needed, that is. For most things, if you're smart about exactly when to use LA and keep an Ewer saved, you should be fine.