My brother Jeff used to talk about the third wall. When you’re painting a room, the first wall is easy because you’re excited about getting a chore done. The second wall is OK too because you’ve found your rhythm, and the fourth wall goes pretty quickly because the end is in sight. The third wall, though—that’s the killer because you’re tired, you’re bored, and you can see how much you still have to do.
He and I used to talk about the eighth bolt as well. We assembled an Ikea bed frame when I moved into my first apartment in Toronto; the first seven bolts went in smoothly, but getting the eighth one to seat properly took half an hour. At one point we were holding the partially-assembled frame upside down and shaking it to try to get the damn thing out so we could start over.