Just to make sure my model of this is right, the layering here looks like (arrayed spatially from top to bottom):
NFC scanner
air
wallet side
work access card
aluminum foil
other NFC cards
...
wallet side
This aluminum foil is then used to block transmissions to and from your other cards through your wallet, meaning that you can only use your work access card through your wallet?
Almost! I open my wallet first, so the "wallet side" layer is just a half layer holding in my cards.
The gates in the lobby of my workplace annoyed me for years: they would often reject my access card, and I'd need to tap several times. After a while I realized that the reader was getting confused by the other RFID cards in my wallet, and if I pulled the card out of my wallet first it worked every time.
This turned out to be very easy to fix: tape a piece of tinfoil to the back of my access card:
I feel a bit silly that after spending months pulling the card out each time the fix ended up taking me a couple minutes. I often decide to put up with minor annoyances instead of thinking about whether there's a way to fix them, and I think overall that has made my life substantially better, but in this case even a little thought would have been well worth it!