https://www.rollitup.org/grow-journals/220117-cali-kush-1st-grow.html
He started his seedling on 12/12 and tried to train it...
I think if you LST and 12/12 from seedling you can get 4 plants in there and yield at LEAST 20gs
If everything goes well and you train them nice they can yield half oz each it just depends
my friend pitbull does 12/12 from seed you could also check out his grow if you wanna know more about that
Good Luck