Side branches get more light.
Partial harvest never work in my experience.
Once you remove most of the plant, what is left has not enough energy to mature correctly......they just sit there "sulking" then take forever to finish maturing and due to the lack of energy, the trichomes don't maintain their health.
The second pick buds are always lower in quality than earlier harvested buds from a normal plant, even if slightly immature.
I have tried this many times and the result is always the same, second picked buds from a previously partial harvested plant are always inferior.
These days, I always harvest the entire plant at once and accept whatever is there as it is.