It's really just
"can you do your rotation while doing non-stop mechanics for 20 minutes"
Like if you had to do an entire tier of savage from 1-4 in one go - no breaks, with no to very few deaths (at the right time), on fast forward. and if you wipe, it's back to boss 1.


It just takes time to bash your face against the content while you and 7 others find out what parts give you trouble and how to fix them all at once.
You gotta have patience and humility and the will to keep truckin'.