You really should do one of a few things here.
1) Study, read, research.
2) Experiment and find what works best for you.
3) Hire a trainer and do what he/she says and see how that works out.
There are various theories which answer the questions you're asking, and I've seen people having success with all sorts of these theories being used.
Forget man's so-called logic and find your own metabolic needs.