Yield is all about the production of 1 auxin (IAA), that auxin is produced most at the apical tip.
If you flatten the plant out so that it doesn't have an apical tip (SCROG) then the auxin IAA is evenly produced across the plant producing even colas as large as the plant genetically can.
If you think about water in a glass, when you tip the glass to the side to pour the water out the water level will stay flat no matter what position the glass is in (Sorry about the analogy, I can't be arsed to draw it).
This is how IAA behaves if apical dominance didn't fuck that up, much like the water in the glass. You can use apical dominance and IAA production to your advantage though without any manipulation and that is by growing trees and hanging bare vertical bulbs around the room at mid tree height.
This puts the light source at the side of the plant making apical dominance turn the plant into a big round bush of large colas.
"Low stress training" is too vague a term (I don't mean by you), it needs to have a purpose otherwise it's pointless.
Too many people go bending, twisting, snapping and tying their plants without actually understanding what they are doing and why.
This technique is the easiest and quickest way of significantly improving yield from a seed plant hands down.
Veg to a decent size, chop the top out and about 4 nodes underneath (top 3rd of the plant, ish), steak up the now upper branches (if needed) and flip the fucker.
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