Yes and no. LST will make more sufficient use of your space with less plants.example 10 clones grown SoG would yield about the same as 2 - 4 plants properly LST'd. Genetics and proper use of light is where most of your yield will come from.
Absolutely, when compared to just growing your plant like a tree. Don't be afraid to bend your plants, they can take it better than you think, especially right after they've been fed.
1. Make an outdoor crop look like something other than marijuana.
2. Keeping height down in a cabinet.
3. Evening out the tops of your crop to maximize light distribution.