That policy is basically there to prevent you from “blocking” the airline from selling a seat & then using your travel bennies to get out of paying for it. The airline considers this (fairly, IMO) theft of revenue. As such, my personal standard for this is pretty high. For any same day NR travel I have to feel confident that I could convince a room full of people who are starting with the assumption that I stole $xxx from them that this was actually a legitimate change in plans & not just an opportunity to save money. I’ve easily used tens if not hundreds of thousands of dollars in value on my benefits over the years so I’m extra careful not to jeopardize that to save a couple hundred bucks.

FWIW it’s not allowed in either case but I think the scrutiny is highest when the cancellation happens within the 24H free cancellation window.