I take every card I have that has no FTF's as well as a no FTF debit and my normal debit card. It's kind of like insurance in the way I take an umbrella even if no rain is forecast. I also spend a couple hundred bucks a year for travel health insurance for my husband and me. I hope to never have to implement my back-up plan but I've got it, just in case.

I will say I always give a travel alert (even though most/all of my no FTC cards don't ask for it anymore).

OP, are you looking for the "right" number of cards or something else?