On: Medieval staircases were not built going clockwise...

[usrusr]

That's what I find most fascinating about the claimed 70/30 distribution, I'd either expect something very close to even or far more lopsided.

Perhaps a closer look at the numbers would show a very clear default direction plus a strong priority for symmetry where applicable?

[edgarvaldes → usrusr]

What if the 30 percent are more close in region or time?