Amen Jim. I was taught recently "Perfection and Grace puts a smile on your face", corny but true for a craftsman. You do want precise, tight joints as shrinkage will cause a gap to open up even if the joint is perfectly tight when done with green wood. 1/32" of shrinkage gap you can live with in your home. 1/16th or more looks like poor crafstmanship. And if it's your home, you will notice. That is why I said (as I was taught), leave 1/16th when using the saw, then chisel and pare to your scoreline and use your combination square to make those tennon shoulders and mortises dead nuts. It's amazing how much precision you can get with good layout/score lines and a sharp chisel. You should spend as much time surveying and laying out your timbers as you do cutting. That will save you lots of problems in the end.