From what I could read in mdd_object.c the procfile changelog_deniednext is the number of seconds to wait before logging another NOPEN changelog record.

The implementation computes a deadline once (when an NOPEN is logged) instead of comparing the current time + the timeout. This means that if somebody sets the timeout to 3600s, produces an NOPEN changelog and then sets back the timeout to 60s, one will still need to wait an hour to see the next NOPEN changelog.