The old saying "Measure twice, cut once." is very pertinent to woodwork.
My late father was notorious for cutting wood just a little bit shorter than was actually required. Most people use a tape measure that starts a zero and the day that I found one of my father's tape measures that started at 2" I thought that I was seeing things. After a "double take" to confirm that the tape measure did indeed start at 2" I did eventually get it where it belonged, the dustbin.