A week or two ago there was a gacha where if you spent 50 flower gems, you'd get a bonus five star ticket. How often does that roll around? Should I be holding my flower gems for this event? I think it's clearly the best return for 50 flower gems that I've seen so far.

So I have a few questions:

1) How often does it come around?

2) Are there any better gachas?

3) Are the increased rates for gardenia/oxalia/nerine overall more worth than an extra guaranteed five star draw from the ticket gacha?