Photoshop :: Way To Dropdown Mountains / Trees And Any Repeating Landscape

I am making a fiction map. I want a fast way to drop down mountains and trees and any repeating landscape. I figured a good way to do this would be to draw said tree or mountains and then set it to a brush preset, add some size jitter and spacing.

It works well except for 1 problem. The brush drops down images that are vaguely transparent so when 1 mountain overlaps another, it creates an overlay that looks horrible. As if the brush is 50% opaque.