Worth upgrading S normal cards with same theme to R? I've started this game about 30 days ago, level 23, and about 10\+ S cards. I noticed that if I have an R card normal, there's literally no way I can convert it to signed/prismatic. So if I get an S card to R without signed/prismatic, I might end up with a dead R card in the future if I get a signed/prism A/B/S card I can upgrade later.

Currently, I'm waiting for signed/prism cards so I can upgrade to a signed/prism R from S. I think that's the best strategy, right?  It does make it harder to win the league though without a surplus of R cards, but then again, the league rewards don't make up for the 50,000\+ RP needed for S to R upgrade.