We have three credit cards too but rarely use them and pay them off ASAP.
They are for the convenience of internet purchases and traveling.
I have several “cash back” credit cards that I use for almost everything. You don’t get a discount for paying cash, but you get money back for using the cards - doesn’t make sense to me, but I’ll go with the flow. I started using cards mostly at gas stations because when paying cash I’d inevitably get behind some nitwit who wanted to buy a dozen lotto tickets, but couldn’t decide on what numbers he/she wanted. A trip to the actual cash register at the quick trip is an excruciating experience that can take anywhere from 5 to 15 minutes depending on the number of dimwits in front of you.
Yeah, they are great for that especially if you pay them off inside the billing cycle. I haven’t had one for awhile. Still, it’s a necessity these days for renting cars (which I don’t do much of anytime anymore - used to do it every week for the better part of 2 years).