HERE, at least, they close the TRAIL that goes to the lift in the back at the time they say the LIFT closes. Theoretically, they then sweep, so it's unlikely that you'll find yourself stranded. The big secret here is that one lift actually closes 20 minutes or more AFTER its official (on the map) close time. The reason is there are a multitude of ways down into the basin it services off the main lift, which does in fact close at 4. But, given the huge number of ways to then depart that lift and end up at this other lift out of the basin, they allow the "receiving lift" to stay open longer than posted. It's a great way to get an "extra" ride at the end of the day.
The lifties HAVE jokingly pretended to close it on me, and told me I skied past closed signs and I'm SOL, but since I knew better, I just laughed. I know that unless patrol passes you on the groomed run, you're fine. And they won't pass you, they'll trail behind you, herding you down the hill. One thing I DO NOT DO is go off the groomed run into the other areas because patrol could easily miss you and there is no cell phone service down there. Theoretically there is a phone, but I wouldn't trust it and the way out is so tough and long, someone stranded would be in big trouble.