I have been writing the current play for far too long. The idea has been niggling at me for some years, and I made two or three false starts on it. But now I not only have a first draft of about 70 pages (not bad for something that at one point seemed likely never to make it to 10 pages): I even have a final scene.
That doesn't mean the play is ready for people to perform, or even ready for people to comprehend. I have a sense that the order of some scenes is wrong; that I have glossed over some stuff the audience needs to know; that at least one character's story line just fades out instead of coming to a good stopping point.
But now that I have the last scene, I know tons better what this play is actually about than I did when I started. And it's hardly about what I thought it was about, at all. I couldn't find the ending and couldn't find the ending, and the other day a character whom I had last seen about 20 pages earlier walked in and handed me the ending.
And now that I know better what the play is about, I can go back and spackle the awkward bits and expand the terse bits and get the thing to a point where some readers can sit around a room and read it to me. Here comes the fun stuff!
Getting to the end of a play gives you a gift that getting to the end of writing an article or an essay rarely provides: the characters have come alive and take the direction of the story out of your hands and show you how the play has to end even if it isn't how you thought it would end or wanted it to end. I think that's why I keep writing these things: there's a surprise at the end almost every single time.