I fimmed for a while but had spotty results. When I top, they always get two more tops. I've topped lots of branches on a plant at one time while in veg and didn't have any trouble. It just ended up with a lot of tops. Now I top only once, then lst by holding each top down (after the two tops get taller) with fishing weights, one to the left, the other to the right. This is all during veg. Then in flower, after about 3 weeks, when it's about done stretching, I supercrop all the branches in multiple spots by pinching the snot out of them but not cracking the branches. It takes 1-2 weeks to recover from this, then puts up a bunch of colas.