I've been practicing SCH for a couple of weeks now and I think I have a good handle on everything except Aetherflow stacking. Basically, I'm finding myself in an odd situation frequently where I have one or two stacks on hand, Aetherflow is off cooldown, and I don't know if I should save the stacks or refresh them.

For example, on Titan, I have 1 stack. I know Mountain Buster is coming up in a bit. Should I hold onto that one charge for Sacred Soil and then Aetherflow, or should I go ahead and Aetherflow to refresh to 3 stacks so Aetherflow can go back on cooldown for a potential of 6 stacks later?

That's just one example, but is there a general rule of thumb for when to use Aetherflow, or too situational?