Do old holiday hours entries eventually get deleted?

I'm noticing that I have about a month's worth of old Holiday List & Call Handling events. Are these old, expired entries eventually removed automatically, and if so, on what timing? I'm asking because I'm using the API to display this as a call coverage schedule, and also to control access to updating that schedule. I'm trying to decide if I just filter the list by date, delete old entries to clean up the list, or some combination of both. Knowing the behavior will help the decision.

Thanks in advance!

Steve Speck