Originally Posted by
Sunshine
From what I've read (by nightcrowler, etc), they just keep shredding (or rake/mangle/SR if those run out, of course). I think the exception might be if you're near the end of berserk, when you know that you can't use up all of your available energy pool.
Even though it seems like a waste of CPs, each FB during berserk costs up to 47.5 energy**, which is enough for just over 2 shreds. In a simplified format, if your average shred crits for 9k and your average FB crits for 16k, 9k * 2.x > 16k. (Of course there's more math to be added for reg. hits, crit rate, and so on, but the consensus among people who have actually done the math seems to be that you should just shred.)
** Of course if you'd have less than 47.5 energy, it would use less, but you really should try to avoid running out of energy during a berserk so that you can use every gcd.