I have, just last trip in fact. Not as lucrative as summer, but still definitely happening, at least on my PM schedule.

But I was specifically talking about the Release-to-check-in when it happens. To pick a random example, let's say you are assigned a 6pm report for a trip the next day, and you do the release-to-check-in. The odds of you getting reassigned into a different trip are much lower than if you were still available for an assignment beginning at the start of your RAP. Yes, you'll get LCO if your trip changes, but if you're no longer on reserve, that change isn't nearly as likely to happen.