So from what i saw, on DMM they have 3 different kind of general sheets, each with 16 types meanwhile here on Nutaku we have only 1 set of 16. So i dunno if you can rely on them. Nevertheless, it's better to get i guess all the drops because all can help you.

So from what i saw the event is like :

1st Phase you can get access to crappy rewards from stages - maximum 500 bags for 80 stamina which is the most decent reward, but a lot of stamina required. And for all the bags you can invest in the first 10 card sheets that are available. Also, EACH DAY starting yesterday, a Full house sheet appears. That's a bonus card sheet, the golden one. And from what i saw, you don't need to earn all the rewards in the day it appears if you don't want to . You can select what sheet you can want from select sheet menu either it's completed or not. It just must be available.

Then the Bonus Stages appear - the New Year stages, with also some Special Full house sheets - on 1,2,3 of January.

And then 2nd Phase commences, with the bonus secret-garden-stage-like which gives tons of bags, and gives access to the last 6 card sheets you can complete. And also the daily full house sheet .

From what i saw, the only Priority-time-based stages are the Special New Year, which i guess are limited to that day. That means if you don't manage to get the rewards on the 1st of January from the Special New Year full house sheet, which is the 1st one, i don't think you can do it tomorrow or after the day passes in another day.

But for the other things, i guess it's ok.

I consumed at least 20 FG just on this event to be ok with almost all the card sheets, but my advice would be, keep your bags for the New Year stages (13500? i guess?) and then invest a lot of stamina in the 2nd Phase where even you make a 15 stamina stage you might get that bonus stage that gives you 880 bags or 35 bags/stamina.