Questions for collectors

[JKooch66_XBL]

Last year I did all collections NMS, but I didn't do it optimally because I started late and wasn't familiar with where cards came from and when. This year I'm keeping track of everything. Live series and stuff from packs are easy enough because they'll keep releasing them and there will be flash sales to tank prices, etc.

My questions mainly revolve around the RS, BR, and event rewards. I mainly grind solo and have to buy this stuff. I'm keeping a spreadsheet of everything so I can keep track. The main question is, when's the best time to pull the trigger and do these cards ever come back around? Like should I grab all of the BR cards right before this one ends or do some of these same cards come back? Same for RS.

And for events it says that for events that share a theme, whatever that means, cumulative progress will carry over from even to event. I'm not really sure what that means in terms of themes. This first event doesn't seem to have a "theme" so are the 2 diamonds on there gone for good after this is over?

Lastly I remember last year something happened and a bunch of people sold a lot of these online reward cards and prices tanked. I don't remember why or what happened but I remember people cleaning up on the online reward cards. Is there something to be on the lookout for that causes this?

Tldr: What's the most optimal way in terms of timing to go for RS, BR, and event reward cards?

Thanks!