It was 405 minutes we had the CNC mill available to make parts that could ONLY be run on a mill., instead of using it to make parts that ought to be made on a lathe.
Two of the basic principles I used to emphasize is to (1) use the best process to make the part, and (2) use the lowest cost machine capable of doing the work. For a part that is already on a lathe to get turned the best process is to tap it in the same setup, and our lathe cost about 2/3 as much as our mill and the hourly cost is lower. In a small shop like ours we sometimes have to do things inefficiently but we are always looking for ways to improve our processes guided by basic manufacturing principles.
I realize that a lot of what we do and the tools we use isn't really applicable to the home shop craftsman, just as what General Motors does isn't really applicable to a shop our size and capacity; it's all a matter of scale. But minutes are minutes and have their own cost and are in finite supply, and we try to use them efficiently.