I used to keep my no AF Citi cards forever. But we have a new policy for recent Citi cards. We meet the spend, wait for the miles/points to post, then cancel.

(Except for TYPs cards, because TYPs are tied to the card, and not to an separate account, and expire 30 days after you cancel the card ).

Citi is in effect forcing us to cancel right away, because you can't get another bonus with the same card still open, and the new rule is not just when you applied, but also when you closed one. So the quickest way to qualify for a new bonus is to cancel as soon as possible to start that 18 month clock running again.