I seem to get similar plant size/yield give or take, in most plants that I grow these days. Especially now that I don't do hardcore LST tie downs much. I do top and lollipop and open the canopy up as needed. I did notice that SN did not want to be tied down, even though I really didn't plan on it. So I dunno if that helped it, or others are doing a lot of pinning of branches, etc. One reason I got away from doing that is because I felt that it was stunting my plants a lot. After they are topped, I defoliate here and there, tuck some leaves. And let them go. Once they are tall enough, I have grommets I install on my fabric pots and I use soft garden wire to open the canopies up for even light to the fruiting sites. It seems like I said, that when I started doing this vs wanting to control the plant, I get repeatable results on most strains. You can check out my grow thread linked in my signature below. Also in that thread is the monster Twisted Tree AMR auto that was engulfing almost an entire 4x4. Unfortunately, we got wind that we had to move so I had to cull it.
Anyway, yes I was shocked by the size and quite possibly a unicorn. I kinda sprouted it knowing it would be smaller and something I could tuck in a corner and enjoy. And obviously it went against the Mephisto descriptor for behavior. I have seen a couple others on Reddit with pretty big SN plants as well.
As mentioned we just moved. So I'm just now getting one of the tents back up to run a couple. I'm doing Walter White next and something else. But I will be curious to see if I can get a repeat SN fairly soon. Smoke is great though.