The only issue I've ever had with trail maps is my first time at Mammoth. For those who aren't familiar, there is actually a sort of valley between the first set of chair lifts and then the summit, so you can't actually go from say the summit to the top of high five express lift even though it looks like perhaps you can, you have to go around this front ridge then work your way to the top of the high five express lift. On the trail map painting, this ridge is pretty subtle and hard to appreciate without already knowing about it.

I love that route to the summit :)

That lift exit at the top is a blast.