Yes. I do a day in the refrigerator and a day out. I have a mini fridge that I keep on the warmest setting so it's cold but not super cold. I've done up to 3 days in and they've been fine.
Hornworms are a lot of water. They will make your chams poo very runny if you use them as a daily feeder. I give one a day or a couple every other day when I have them but no more than that. They are great to help hydrate though.