I never really cared about this when it came to artwork. Unless you are drawing a real person or your intention is to portray someone realistically, I don't see a problem with tweaking the scale of certain parts. If you can draw hands really well, make them babies huge! Hands are one of the hardest things to draw! I don't know, I deal with professors that always comment on the size of hands, head, legs in my artwork and I always have to explain that I wasn't going for absolute realism like I would for say, my life oil painting class (painting the nude figure). People are so nitpicky about that! Sorry I don't want my prints to look like a photograph! If I wanted to do that I would have taken a photo!