I FIM’ed my plants after they grew their 4th set of branches and a top sprout popped up. After 5 days they all just kept growing straight up as if nothing happened, rather than sprout 4 side stems. So, I topped them, snapping the new top off. I’d like to get 4 colas each like FIM’ing is supposed to yield. How soon can I top the 2 new offshoots that will grow as a result of the top?
Fim’ing is unpredictable. I don’t know what or where you heard it will give you four tops. It could make more than just four, and they might not even come out of the stem symmetrically. You have to get it just right (“or just wrong”, as the name implies) to get the desired results of numerous tops shooting out at that node height.
Traditional “topping” almost always results in the desired two new tops from the next node down. If you then let those two tops grow up a node and then top them, you will have your 4 tops, two new tops coming from each of the 2 tops that came off the central stem you created previously.
Does total yield increase the more you top or just more buds with same total weight per plant?
It depends on many factors, you can over do it and yeild will suffer. One of the biggest factors is the size and shape of your area and the type of light. The idea is mostly done indoors to make the most efficient use of the light available, training a decent top, to maybe as many as four per about each square foot, and creating a uniform canopy of tops for a similar situation to a sea of green.