When building something using mortise and tenon joinery that requires four posts and a bunch of rails and stiles (a large bookcase for example) make sure all of your stock is square.
Square stock is a key. I have made many mistakes of “assumption”—that the blade is square to the table, that the miter gauge is square to the blade and most importantly, that the square I am using is square. Jerry
I have never used a center punch to do this. I use a small ball peen hammer - works great and the marks are barely visible. I have done this for more than 60 years!
I begin a new set of blades with fence far right. Given the various thickness that get jointed the wear on the knife goes from some to none over say about 2". The result is an edge taper on a 2" wide board. Not a problem with edge gluing for I by habit flip panel pieces when jointing to cancel this angle of the edge. But if I am jointing 2" legs the error can be significant.