Some cards may require a fee upfront, other may offer your 1st year free. Still other might never charge a fee. So churning doesn't necessarily mean you have to pay a lot of card annual fees.

For Marriott's 3 cards, only one of them requires the annual fee to be paid upfront (the Premier Visa card.) The other 2 offer your first year free. So you could get all three of those cards in a year and at most only pay one annual fee.

I would suspect that Hilton branded cards are similar with some having an upfront annual fee, but others without a fee (at least for the first year.)