This is a great question! The feature you're asking for can't be done out-of-the-box through configuration today, but it's been on the roadmap in the past, along with a large number of other promotion ideas.

If you want to do it today, it can still be done but would require a bit of development. You can create promotions that are inactive and have a scheduled job that turns them off and on at specific times/days by programmatically updating the promotion.

Good approach Will! I was going to suggest something with promotions and getting them granular down to Time vs just Date, but turning on/off products... or for that matter, updating the price with scheduled job, or turning on/off promotions by scheduled job.

I like how this suggestion would achieve the action while not having to affect the core logic/process for promotions.