Here's a dilemna: You have a sign, for example, with a large field, and raised letters in an intricate font or artwork (a pocket with intricate islands). To get the best surface for the field you'd like to use the largest straight bit possible, say 1/2". The problem is, your final pass with your fine bit, say 1/16", would take forever because the 1/2" bit leaves a lot behind. You could use a 1//4" or 1/8" bit to do the clearance pass, but that would take forever too. How do you resolve this?
I discovered a cool trick. In the above example using the pocketing toolpaths, select 1/4" as your finish tool, and 1/2" as your clearance tool.
Now, do the same thing, instead select 1/16" as your finish tool, and 1/4" as your clearance tool. Then just delete the 1/4" toolpath that was just created.
In this way, the first operation would be the 'rough' and 're-rough', and the last operation would do all the detail work. It's an extra tool change, but in many cases this would be way faster than using a small tool for clearance.
This also works in Cut3D as well... saves a heluva lot of machine time!