Ok, well "snarky" was not my intention. Though it does seem like a trolling first post, maybe I was to quick to judge. So, I will continue to try and help.
My apologies.
Ok, well a percentage is definitely unrealistic because of the following variables: medium, environment, strain, ect. And by size, I would assume that you meen height, correct?
In that case height can damn near be cut in half.
But in terms of size, some good LST can actually just take what you would have had in vertical growth and send it horizontal. Some of us, myself included, tend to just bend autos over in a 90° style. This gives the plant the ability to make every growth node branch a "main" cola type of growth.
I hope this can help. I'll get you some pics of one example of mine shortly. Maybe some other members have more input.
