That, and the average age of your credit accounts is also a factor. If you're constantly churning cards and don't keep any for a length of time, your report will be full of a bunch of new (some open, some closed) accounts, and so the average age of accounts will be relatively new.

If you've had 30 years of credit history and many old installment loans and cards you've had for a decade, then a few new, churned cards isn't going to do much to lower your score, but if you're young with relatively little credit, your score can change dramatically (and then you might find yourself having canceled the card and then unable to obtain a new one).