Not true. There's plenty of information about how to maximise income by hopping proportional and scored proportional pools.
Got a link? How can you predict luck?
You don't. You can calculate 'when to leave a pool' and not loose much, but there should be another pool you can jump to, which is the guessing part, that makes it not worth it IMHO.
Hmm, I'm not sure Organofcorti was thinking such a simple solution and I for one would like to know more...