You can keep them super low if you want. It takes some time and works but they come out awesome. I am doing a CLF grow so I need the plant very close to the lights. I have been LST training them from very early on and they are only about 6 inches tall but fill all of the the space for a 5 gallon pot. The LST training works awesome, Kinda like bonzai on yer weed. Now I have not one main bud site per plant, but 6 on each plant. LST provides the plant with an even canopy which helps it receive maximum light and bigger yields. Plus they stay very short. It's pretty bomb.
Check it out,
Good luch