OAuth refresh token lifespan

Hello,

I've been using the OAuth2 authentication method as explained here in order to use the Bulk Data Insertion API in Adobe Analytics.

Everything worked fine so far, however I had a recent issue with the authentication data being expired. I assume this is because the refresh token wasn't used for a long time, and therefore expired. (Re-logging and re-creating authentication data worked fine)

My question is: how long is the refresh token lifespan when not used? A quick google search indicates 60 days, documentation indicates 14 days, and I'm stumped to find out which to follow.