Barbara Samuel has a fantastic article on organic plotting which made me say "Aha!" and now I must get Story by Robert McKee. This is very like my process except without the Story exercise and also lately I have not had a year or more to "cook" ideas. I think the reduction in cooking time can be compensated for by the Story work recommended. (It is possible to accelerate cooking time and the more tricks available to do it, the better off a story is.) Also, instead of collage I do music soundtracks to generate the right tone and mood.