Height, roots and stem thickness. Right now they aretoo tall(height) they fall over. So they are growing more roots and making thicker stronger stems so they can grow taller.
Once you pass a certain point you don't yield more weight in bud, you just spread it out. So you can have 30 tops with 1 pound of bud or 100 top with 1 pound. And the max weight will depend on what your roots will support.
Your suppose to do it during veg time a few times before flipping so it's less likely to stress and hermi on you. Now, I would only do it if you have high humidity, because mold(pm) will wipe out your grow.
If you leave it like that you will have a much lower yield, you are wasting your best light on one bud. Bend it over, tie it down, and then lower the light. Even if the branch breaks off completely, you will yield more without that top.
My first grow had these, I added a layer of arogonite(like beach sand) i got at the pet store on top of the soil. It'll keep the top of the soil dry and get rid of them and kill their eggs. Just water really slow so you dont have to keep adding more sand.