One drawback to scaling the same symbols up and down is that the line weight expands and shrinks too. One would expect a hand-drawing cartographer to use the same or really similar size pens. If you want to depict markedly different sized peaks, which is a good goal, you'll pretty much have to draw them differently sized from the start.

Note you're depicting all the same *type* of peak - the young, sharply hewn ones that may have seen some past glaciation. If you go to a bit less detail, the eye says "stand in for any kind of mountain". This detailed or more, the viewer starts to expect that you are enumerating specific mountains or at least representative real ones... Think with your tectonic scheme which ranges might be older ones ( Urals, Appalachians, Ozarks) and which younger ( Himalayas, Rockies, Alps). If you want to show that level of detail, then draw you some rounder symbols as well.