In high-school, I played the snare drum in our marching band. When you’re on the field, if you are instep and in the correct place, but everyone else is out of step, and in the wrong place, guess who the crowd thinks screwed up? Measuring can be thought of the same way. If you do one piece correct, but everything else ends up off, then the one correct piece can become an eye sore. To fix that, cut your first piece, and use that as a reference for every other piece. The measurements on your plans are more like guidelines. I am in accounting at my full time job, and I like numbers to match up to what they are supposed to be, so I’ve had a hard time adapting to this myself, but it works.
I’ve found it to be tricky. When I try to cut things to the same size, I often end up custom fitting each joint anyhow. Sometimes it’s easier and faster to do small assemblies in a well-thought out sequence. If I do measurements one-at-a-time, things usually turn out better, especially if there are surrounding parts to indicate what the part needs to be.