Okay, so I'd like to add my 2 cents. Over the last 30 years, I've planted and maintained numerous vegetable and landscape gardens. When I think of the plants that shot out or stretched when they went into flower, its endless. So I would have to assume, an outdoor grow with all natural environment and light source, proper nutrients is as natural/normal that your going to get. If that strain stretches under perfect outdoor conditions then I'd have to assume it's a genetic characteristic of that strain. Now if it's stretching in its natural conditions, then I'd also assume it would stretch somewhat indoors too....but it shouldn't stretch MORE indoors if the indoor grow environment is flawless. As far as I know, you can't come close in quality of light indoors as compared to pure direct sunlight, so hypothetically, less light indoors = less stretch.
Its not often that I come across a perfectly dialed in indoor grow. It took me 5 years of trial, error, hitting forums, researching problems. So many things I knew but yet were blind to them in my own grows. Up until now, they all had one thing in common, insaine stretch. I think eccessive stretch takes away from an otherwise great grow and bud. It makes the buds real wispy/airy. You dont get those nice tight dense buds from a plant that should be producing them. I added a co2 system that didnt make a noticable difference. Recently, I took a long look at my grow, realized a few problems, made corrections, and omg what a difference. These problems were temperature, light intensity, and air circulation. My room temps were 85-90F, 80%, in a sealed room. My changes brought temps down to 72-76, continued with the co2, added a fresh air/exhaust system, and the plants responded incredibly. Bushy plants intead of tall twigs. All these grows have been from the same mother over a 5 year period. I'm very familiar with these girls. I can positively say that correcting these two issues made the world of difference.
The second being my light. It was wayyyy too close. I'm still a novice in the light area, but I think closer is not better. My 600w was running about 4-5" away, I moved that up to a minimum of 16". I have a chart that I'll try to figure out how to post, I think its a PAR chart. At 4" my plant was getting 1735% more PAR that it would normally get outdoors from the sun. Intense light~photosynthesis~high heat all contribute to stretch. In my opinion, in Guitar Mans photo, the plant on the right is stretching from being so close to the light. Its trying to allow internal heat to escape so it stretches allowing airflow through the plant including the buds. But what happens? It gets closer to the light making things worse. The plant on the left is much less stretchy, but the light is at a much safer distance, resulting in a less stretchy plant. Just my opinion Guitarman, great looking plants, but I think some of that stretch is light stress.
The sativas dominate in size over indicas. We all agree on that i believe. Sativas.... equatorial (very hot/humid) strain. Genetically implemented in characteristics of sativas to stretch to help with airflow through plant? Indicas...colder climates, less intense light.....doesn't need to stretch as much due to colder climates.
Hope this helps. Im in no way an expert but this is based on my own research and experience