Although I have a stool at a convenient height to my R/C worktable I find myself standing at least 95% of the time. I think the answer to your question is a function of the size and scale of the subject. Large airplanes require one to cover a lot of space reaching for things, leaning over to align something, or bending down to dig the next parts out of the kit.

On the opposite side of my building room I have another workspace devoted to static display 1/24 race cars and 1/12 motorcycles. Because these models are so small everything is within an arms length and I sit 100% of the time.