I've had real good luck with this feature. I recently ran a job that had 6 tool changes, used the rest robot, and the time OneCNC calculated was 8 minutes and 26 second. Actual machine time was 8 minutes and 42 seconds. I attribute the difference to tool change time and that OneCNC figures rapid moves at 10000 (which is cofigurable). So I should change this. Just need to figure out what to change it to.