I don't.
That is because I collect a lot of different types of cards and thus I only junk cards I know I don't collect. And for some types of cards I like to collect duplicates as well that I can then gift to friends or region mates, or use to trade for other cards.
When I open packs I only junk:
- Cards with default flags that are not in one of the region that I or one of my friends collect are junked.
- Non-default flag cards I know I and nobody else collects.
- And both only if they do not have any JV or higher bids, inflated cards get transferred to catch MV sharks, or get gifted to friends to get them a gold badge.
And when I process farms I then check if all the cards I have left on my farms are already in one of my collections, or one of my friends collections.
This also means I have a huge backlog of cards that need to be transferred and/or checked. And thus a lot of potential bank.
But I rarely farm these days since I have to process a 29k backlog of cards that need to be either junked or transferred to one of my gazillion collections. Opening packs would only increase my backlog.
This is how I ended up with 25k cards in my collections as well, an estimated 70%-90% of those come from my farms.