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It's not a strict rule, but more like "If I were a writer I never put 'c+без' together". Real speech can be ugly sometimes.
I think it's better to say in the way I told.

> I'll stick to 'civilian' method
Oh, there is nothing wrong in "military" method. Moreover it can be preferebale in many situations. It is naturally more convenient in computations/comparisons or...

"с двенадцати минут (девятого) до примерно половины девятого"
good. "девятого" can be omitted.
"с восьми двенадцати до примерно половины девятого"
it's ok. a little bit worse, but a very little...