yeah you can top or fim anywhere. well that's what i did when i was trying it out.
i did about 7 fimms and a few tops and it took about 2 weeks to get back to normal but now i have multiple head on all branches.
i had heaps of locations available for fimming because of the LST i was doing where the plant is basicaly horizontal with the soil so every internode gets two branches that grow vertically of course.
so i cloned half of the little branches and fim/topped the rest and no i have as more little branches than before i started.
i have several that got 4 heads + the 2 little ones that grow at those nodes (which have since been left behind).
the problem is now that there are so many heads, some of them flourish as they get direct light whereas the ones on the outside seem to grow slowe so i'l be LSTing the hell out of all off those branches soon too.
so just so you know it can actually get out of hand with the number of tops you'll end up with. i think i'm creating a monster.