That's not to say that I won't know what some of the fill might be. For instance with today's puzzle, I knew that I'd wanted 1-Across to be that answer so I designed the fill and pattern around that. But generally it's a bit of a suprise what things come up as I'm filling in stuff.
There are times when filling in the grid, where I notice I might be able to fit in some either really eye-popping Scrabble-y letter combination word or phrase. And generally, once that "aha moment" occurs, nothing shall stand in my way in order to cram that entry in the grid. If there's a way that WIIITIS has a potential home in one of my puzzles, silent movie actress be damned, she's going in there to make the fill work.
Interestingly enough, I find that the places where a lot of these new and exciting entries appear are in the fill spanning two (or more) theme answers. I'm sure that other constructors notice that trend as well. I recall one puzzle where I noticed that I could fit BILL HICKS in the fill, spanning across two locked-in theme entries. Well, once I noticed that, there was no going back. I was going to fit that entry in the grid, goddammit. Ripped the whole grid apart, actually. And that saved an otherwise mundane puzzle involving phrases using punctuation marks. (For those keeping score at home, I clued the Hicks entry as "Comic to whom Radiohead dedicated their album The Bends.")
Cluing (really one of the most thankless parts of puzzle composition) can yield moments of wonderful I-can't-believe-those-two-entries-lined-up-right-next-to-each-other moments. Last Friday's New York Times puzzle, for instance, had consecutive down answers QUART and PINT, yielding the consecutive clues "Two 55-Downs" and "Half a 52-Down." (Retyping those clues leads me to this bizarre side tangent: Friends of mine were in a band called Barbaro. The B-side on their wonderful 7" [buy it here] is titled "Two Boozlers and Half a Poundstone." I'm sure the title meant something at the time.)
It's amazing to me: when I sat down to write this ramble, I was fully expecting at some point to go on about the breakfast test, but here I am, going off about Bill Hicks and my friends's obscure metal band. Maybe the randomness that happens in the stream of consciousness, also happens while making a puzzle. It certainly seems that way. Whether this is a product of the rules of puzzlemaking, or the scientific fact of how the mind works, the moral remains: you don't want to be in this mind.
Okay, enjoy this one. New puzzle and rant on Monday.