I'm sticking with the 2* strategy (even if my 2* is lvl 29 and quite affectionate, but 600-1100 damage gladly doesn't make a dent in any raidboss over lvl 45, which are the ones that matter).
Only exception: if I see a raidboss has less than 15 minutes left, then all bets are off and I might nuke away, which I think is a fair strategy, given how most boss timers last several hours.