you can lst mid or late grow, but what you are looking for is the side branches to keep up with the main cola in veg by using LST. When in mid grow of preflower, most vertical growth stops and lst wont make much difference at that point. LST is bending the plant over or tying it off in veg, to get the cells to elongate. Auxins move to the darker side of the plant, which cause the cells to grow larger, than corresponding cells on the lighter side of the plant. LST simply wont work in flower, BUT what you can do is pull the side branches down and out in mid flower, tie them off so you get better light penetration, even on the lowers on autos will get huge doing that. Then, in late flower, you will have to tie the side branches up, for the weight gain...and there will be a weight gain with doing these 3 things. There will also be different aspects between autos and photos, but the only difference would be on photos, you would lollipop, top, fim, or supercrop. But the top 3 are primarily for autos.