hello! not a silly question at all! in general I do like to start off my drawings pretty big so it's easier for me to go in and work on smaller details, then when I'm done I scale everything down to a nicer size! so my undertale drawing was just really huge to start with.also, I usually find myself eyeballing my perspective rather than using grids, but only because it seems to serve the style I'm after well enough. if I were concerned with a more geometric or realistic look I'd probably make my life easier and use some guides. I think it wouldn't hurt to experiment with both.thanks for asking!