It’s like the 2.5D tutorial but only the last step. You will use every cut pass twice. The first “rough cut” with a small allowance at smaller depth of cuts if needed then the second “finish cut” with no allowance at full depth, sometimes even faster travel rates.
I would/do make small test cuts on all material to test my settings. When I mill my own frames I make a small rectagular test piece with a screw hole in it and test with that. It makes the actual cuts much less nerve wracking! My only other advice is make sure to triple check your rollers to corner measurements to make sure you are cutting square before each cut.