I have been a carpenter for thirty years or so. I started out as a framer on single family homes, where I used the flat carpenter’s pencil. Its sturdy lead stood up to marking rough lumber but was a little tricky to sharpen. You want a flat chisel point not a conical point. This is accomplished quickly and easily with an inexpensive Keson pencil sharpener.
My framing days are long gone, thankfully. I have worked in many aspects of the field, from general carpentry to boatbuilding to cabinetmaking and am currently installing interior doors and high-end trim. Through it all I have held on to that flat pencil. It never ceased to amaze me how many employers (and I’ve been through a few) have told me to lose the flat pencil and get with the program and use a round pencil. To my mind, the only thing a round pencil is good for is taking a lunch order or making out the bill. The point breaks easily when marking wood and is difficult to sharpen unless you have an electric sharpener under your chopbox, which many guys do.