The “100 ideas” method is straight-up stolen from an anecdote where Judd Apatow tells someone to do it. He probably invented it, maybe? It legit works.
By the time you get to idea #64 or whatever, or sometimes idea #3, you know that at least some of the ideas you’re having aren’t going to make it into the finished thing. So, your job is no longer “to solve my spec script,” it is just “to come up with 26 more ways this story could go.” You stop trying to be good, and just blurt stuff out. It’s sort of like an interrogation method, where you keep asking “Tell me where the boy is” over and over until the kidnapper breaks. Except you are the kidnapper. And also you are the cop. Writing is complicated.