Data point: I’ve been a relatively heavy CC churner for several years, keeping many accounts for only 3-10 months. Due to a recent military Reserve mobilization I did not make any new applications for almost 1 year and closed all but 3 or 4 longstanding accounts prior to deploying. During that one year my average age of accounts, per CreditKarma, changed incrementally each month from approximately 4 years to approximately about 10 years.