crooked big sticks are common. with luck your sawyer carefully chooses how he cuts to minimize these lineal errors. we all know wood grows perfectly straight like it was steel
when laying out a not so perfect stick using whichever _____ rule system you choose the result has to approach joinery points so their planes properly align and fit. once you are sure these joinery systems will come together they may still require some tweaking on assembly. making tenons a tad smaller on one cheek, ofsetting a housing a bit, changing the depth of a housing to fix a virtual plane are all techniques to bring it together and have an overall square and plumb structure. you may still end up with visible imperfections but that is the joy of our craft and the beauty of wood.
