Or so it seems. Sometimes when I manage to get into it, it runs more smoothly that way. But maybe that just shows I was vacuuming the cat all along. Certainly other works come a lot easier, but then, that's a common trait of vacuuming the cat. (What's even worse is that you have to notice you are vacuuming the cat to even try other works. It can take me quite some time to realize that it's this particular story that's the problem, even though it's happened over and over and over again. Especially when I'm cranky and all other stories superficially look unpleasant to write.)
It's not block. Sometimes the scene's a bit hazy, but no more so than other scenes I have plunged right into; sometimes it's exactly when I realize What Has Got To Go that the revision freezes under my hands.