It depends on the situation really. Matches are usually decided in the first couple rounds, so that extra 20% could make the difference in deciding the match, especially since she passive heals your team as long as she's alive. Also, don't forget that she gets 3 attacks instead of 2, so there are extra chances to confuse. You c*so pair with wind main refresh to bypass the cooldown.

With breaktroughs the mystery actually let her use permanently 3 standard attacks since round 3 onwards (and not only in round 3...) that is why the cd is 9 rounds because the 3 stardards + 2 passives and + 30% crit is utterly broken for immortal teams.

It's basically a once per fight thing since:

1. If she's full skillbreak it's a huge heal round 3 to revert any enemy progress on killing her + 3x standards (with 2 of them clearing debuffs team-wide thanks to her passive) the rest of the match with her;

2. She almost always will be paired with another healer to stop any controls on her;

3. Raising her base crit + her 30% passive almost always will lock the ninja in front of her AND if she gets a crit on her chase one more will be locked

It's broken and throws salt on the wounds of teams that already couldn't get passed the first 2 rounds of cancer.