I reached a place in TFFP several months ago where I had written myself into a tangle, and I didn't know how to get out of it. So I stopped. I went back and looked at that tangled-up spot several times, but I had no desire or idea how to fix it.
Of course, I could have written on and skipped that part, but I felt like I had to figure out that scene to build on it with other scenes. (I occupied myself otherwise by meddling with other manuscripts, moving my family to another city, and Netflix.)
If my manuscript was a ship, I'd bailed before I reached a proper port, and my manuscript was well...drowning. (If you think that analogy needs work, the novel I'm currently querying takes place on a cruise ship. I spent many years on a fictional ship, and my brain won't let me forget it. This fictional cruise was inspired by a real-life cruise in 2009. Which was awesome. I want to go back.)
The best way to stop one writing session is to prepare for the next. I find if I type a loose outline for the next day, it helps. Ideally, I wrap up an entire scene with plans for the next scene. It keeps the momentum going. This works for both drafting and revision, I think, although some people like to draft without a plan...in which case, this isn't for everybody. But it's for me. It took me months (and a mass writing spree) to get myself out of my last manuscript tangle, but I'm out of it! Which makes sailing so much smoother...
Copenhagen Harbor, taken on our Baltic Sea cruise in 2009. I love these Danish windmills!
Footnote: This method doesn't account for the times you just have to WALK AWAY from your manuscript and breathe, no matter what tangle it happens to be in at the time.