Yogg 25-man phase 1

My guild is doing pretty well with Ulduar-25 now... still a long slog
over a few nights, and Mimiron requires several attempts, but we've
generally got it down. Yogg is a different story however. We've gotten
to phase 2 a few times and done the brain-dance for a while, lots of
fun!

But mostly we wipe on phase 1 due to people "hitting" clouds that appear
to be more than 10 yards away still. And the combat log / Recount are
useless here since the game records no events for triggering cloud
spawns that overrun us, so it's problematic to point fingers and figure
out who needs to change their habits. Has anyone else out there
mastered this phase, and how?
.