Different cards do different things so sticking to a single card will not grant you as much in the long run. It is a hell of a lot easier to manage though.

There are ways it can make sense, but it's often a sign of using a card to stay afloat, maxing it out, and then using a new one to try to stay afloat, now with bonus debt.

It works in my family that we are basically financially independent from each other and have a shared account for shared expenses. As a result we technically have multiple credit cards, but in practice it's mostly the shared card, and occasionally the "me" card. Automatic payments, no fees and cash back makes it pretty easy.

What do you mean? We just paid off all our cards, have 2 that now sit in a drawer. No annual fee, but have had a few emergencies this year where they came in handy. Large, unexpected purchases unfortunately. Anyway, 1 has a $16k limit, other is $11k. They just sit there. We used all the points built up to order gifts this year.

We have one shared card that we both use for everything, gas, food, etc. all budgeted through EveryDollar so we know where 99% of our money is going at all times.