I tend to work at really high resolution. This one is 5000 by 5000 pixels.
I think I could just about draw every strand of fur on my dragon-sona if I wanted to.
Fitting the window in the program is about 17.5% of full size. I can always scale down, though, so it's better to have the resolution and not need it than the other way around.
I seem to recall my final space fox drawing, which was smaller but a large number of layers, taking up closer to 4.5 GB.