Ethical dilemma? You decide.

[Cory]

This rule isn't even worth worrying about.

What are the odds you'll want to use what you already did in it's EXACT configuration? Not very high, most likely. You'll probably want to change the distance between wheels, the exact position of the gearbox in the tubes, the mounting points for motors, provisions for tensioners, etc.

We have a family of parts that has not changed in two years and isn't likely to change again this year. We have machine code for our CNC mill to make each of the three parts that theoretically could be used from two years ago but every year it becomes more obvious that the previous year's code, while workable, needs to be optimized to lessen run time, lower tool wear, increase accuracy, etc and never actually stays the same.

I would argue that all you would have to do is delete all your selected geometry from your toolpaths, go back in an hour after kickoff, reselect the geometry and you've satisfied the rule about previous design. You wouldn't even need to delete all of it, but then you have another question of how substantial do changes have to be for it to be "different". Can you delete a toolpath to drill one hole and then redo it and call it different?