If you take only one thing away from this article, it should be this: Hand tools rely on reference faces. When you use a square or marking gauge to thickness stock or lay out joinery, it is essential that you be consistent about which surface you use for reference. This is important because of human error but also because it frees you from having to perfectly and consistently thickness and square all sides of a board.
With this system, all you need is one flat and smooth face and one square edge. That’s it. The rest can be hatchet marks for all we care (and sometimes is) because all your layout is referencing off the one good face. This system is the key to unlock efficient hand-tool woodworking.
–Joshua A. Klein, excerpt from "The Artisan's Guide to Pre-industrial Table Construction," in Issue Four