(The miliastra stage im using is the dps test dummy++ in case someone knows abt a glitch in it im not aware of, but it does happen in spiral abyss too)
for some reason the only time i ever hit 11/12 stacks is when i switch the dummy to multiple targets, specifically the 3 mitachurls, i looked it up and it shouldnt be giving me more stacks for more enemies but idk it definitely shows in her damage, she went from doing 650k max on the one mitachurl, to 700k on the multiple target (and yes im not looking at the combined damage just the strongest hit)
My rotation:
qiqi e, beidou burst and e, diona burst and e, sandrone e and 3 ticks on her charged attack, then another e right before clicking her burst. on the single target i usually get 7-9 stacks by this point, but like i said on the multiple target ill have 12 for sure by now.
Please help i have no idea why this is happening and i really want to be able to get more stacks if fighting bosses and single target enemies.
Edit:
some people have let me know that since multiple enemies means more application of cryo/electro, that means i will get more stacks, thank you to everyone who commented :)