But yeah honestly i tried to figure out what is best between buffing auto-atk and burst, and i'm using it on burst now. The thing is, if your auto-atk doesnt multihit you loose a bunch of damage.

What i usually do when i don't have burst time is auto-atk alone on first stun, and dragon blood+burst on the second.
If you see you wont have enough time to build a burst bar, just buff auto-atk and pray for a multihit.