Originally Posted by
Flying for Fun
Wouldn't checking out and back in on the same day (splitting the reservation) just extend the "stay?"
Per the Terms and Conditions, yes.
"If a Member checks out of a guest room and then checks back in to a guest room at the same Participating Property within 24 hours, it will count as a single stay for purposes of calculating Stays and issuing Member benefits."
That's from Section 2 (2.1.d.i):
https://www.marriott.com/loyalty/terms/default.mi