Jackster, DownUnder,

I do agree that CNC is not a magic bullet.
However, since the "human error" factor is taken out of the equation, tool breakage happens much less, than when "twitchy handed" humans do it.

When the first, "out of tolerance" part comes out, all subsequent parts will also be.
So modern CNC also uses its software, for inspection of the parts.

If a part does prove out of tolerance, the process is stopped and the bit, or whatever, is replaced.

Duke Fox awoke later and changed the suggested break-in instructions, to get the annealing done...
Please read contemporary instructions, for Fox (and Enya), Meehanite piston engines still in production.