I took a walk on memorial day with the purpose of seeing if I might want to leave the Pentax 40mm f/2.8 pancake lens on the K-3 III most of the time; i.e., how that effective 60mm focal length works for me. I like it so far. It makes for the most compact, lightest weight, easiest to carry package possible with that camera.
The only issue I have with the lens is that it is not weather resistant so I would have to switch to the 20-40mm WR lens during wet weather. I might make those two lenses my favorites for my walkabouts. The zoom lens is more versatile but is larger and heavier.