Real maps have mountain bumps, 'cuz mountain bumps are cool !
So what kinds of mountain bumps are you guys rocking these days?
JRR Tolkien arrowheads?
Or topographically-prone wiggly lines?
What about doing a bird's-eye thing with a shaded area of brown that is simply called a mountain range in the legend like I usually do when I don't feel like drawing that many mountain bumps?