Yeah, "a few centimeters" is a lot, but under 1/4 inch is close enough for most residential framing. Windows and doors are always shimmed to fit the rough framing for this reason.

That's why they make protractors for measuring and cutting external baseboard trim. I've seen a few 90 degree corners, but not many.

Which also makes it a really silly choice for actual construction.

Brick and concrete make a lot more sense.