So, here´s a thought I had after my lazy experiment.
It seems to me that all updos have a ratio or some sort. Length to thickness. Outside of that ration, the updo just doesn´t function like it should.
I mean, it´s common knowledge that if you have thinner hair, you are capable of doing certain updos with less length than those with thick (So unfair). You simply need more length to "go around itself". But it seems like the structure itself of the updo gets ruined by both longer or shorter length compared to the thickness.
The first updo that got ruined for me was the basic cinnamon bun. Some with thin hair could do this awesome staple at just shoulder length. I had to wait until waist/hip-ish. And then around classic-ish, the cinnamon bun just stopped working. It simply slid all over the place, pulled and was irritating.
Updo structure of cinnamon bun x (Waist length/iii-hair type) = Good structural integrity
Updo structure of cinnamon bun x (Classic length/iii-hair type) = Bad structural integrity
A braided version took longer before I could even do it but also worked for longer. But I prefer the Nautilus for the better stability so I rarely did that one.
Updo structure of braided cinnamon bun x (Classic length/iii-hair type) = Good structural integrity
But this is probably due to being able to anchor the braid better. A hairstick through a braided bun, and that bun isn´t going anywhere. Sure it might pull and pinch and be uncomfortable, but it´s not going to fall.
The four braided cinnamon buns from four days ago were both surprisingly cute, super comfortable and didn't budge all day, so:
Updo structure of braided cinnamon bun x (Knee length/ 0,25 x iii-hair type) = Even better structural integrity
Speaking of the braided Nautilus bun. I love the Nautilus. At around knee length, it´s my workhorse and savior on busy days.
But, trying to do two braided nautilus, each on half my hair doesn´t work. It gets this weird effect where the middle part becomes too irregular and folds over or "pops out" in a way that ruins the structure.
Updo structure of braided nautilus bun x (knee length/iii-hair type) = Good structural integrity
Updo structure of braided nautilus bun x (knee length/ 0,5 x iii-hair type) = Bad structural integrity
But where the braided nautilus fails miserably on half my hair, the royal bun (formed of two even thinner braids, so in actuality on each a quarter of my hair) is just awesome. Actually that seems to have even more stability than a single royal bun (formed of two braids, each half my hair)
Updo structure of royal bun x (knee length/iii-hair type) = Good structural integrity
Updo structure of royal bun x (knee length/ 0,5 x iii-hair type) = Even better structural integrity
Solve for X, ladies and gentlemen....
I can´t really get closer to a formula here. But then again, once you start factoring in the structure of each individual updo.... ehh....
Let´s just leave it at that.