Eish brother...
You can, as some varieties grow faster when flowering like most Sativa varieties. LST can be done as much as you'd like, all preference as LST is method to Train the plant to grow the way you want to short of topping your plant - high stress training.
LST is a ongoing process, it slows down close to harvesting but your "top" or Crown of the plant is continuously growing, depending on how you LST it.
Peace