Out of memory (while not) due to adaptive subdivison?

Hi!

I’m learning with procedural materials and while cranking up adaptive subdivison, Blender reports “System is out of GPU memory”, while my VRAM never went over 15Gb of 24Gb total.

Why is that? Looking at my specs, I should be able to go more. Is there something I overlooked?

I can go up to 0.2 dicing scale, but anything below gives me this error.