So before I go into "stretch theory". I need to stop. And wish you a very belated but very sincere happy birthday!!! Sorry was going 10000 miles an hour for vacation and stuff and it's been pretty non stop still. Also happy mothers day to your wifey!
Next. Stretch theory. So its genetic, but its also dependent on plant shape, ppfd, and stored power.
For instance. Prune a plant so that its center is empty and you'll likely see new growths stretching up to fill that void. Same sort of reason a plant 18 inches below the light won't stretch as much as the exact same strain 36 inches below the light. The plant (and here's the kicker) of healthy and in full stride will give itself the best opportunity to reproduce. And it does that by pistols or bud sites. If it has the energy and sufficient light it will fill the "gaps".
But what about shed and derbs show stoppers. Well they're are getting adequate light and are beasts that are in full stride. Leaving that stretch thing only 1 factor now. Genetics. Not much.
So long story short is. Grow it right with enough light, and some strains have almost no stretch. Nothing against the grower, in fact I think it's a big compliment to know that everything is so dialed in!
Keep killing it derb.