I have only two credit cards- plus the debit card attached to my checking account. I've occasionally had a card refused when I was out of the US because I haven't bothered to tell the issuer, so good to have a backup. I'm planning to dump my AA MC when it comes up for renewal and get a CSR Visa since Fidelity Visa, usually my primary card, charges FX fees.
I'm retired now but traveling with the company card was a PITA- of course I had to remember NOT to pull it out for personal expenses (probably grounds for firing) and then to use it for ALL business expenses. Oh, well- I'm still enjoying the perks from all that business travel in the form of lifetime low-tier Elite status with AA, Hilton and Marriott.