That is what Chamfer is, the distance of the start of the retract at the end of each pass.
The CSMIO and Mach however have an issue when threading, the commands from Mach to CSMIO are delayed at the end of each pass and you end up with an annular groove. It is Mach that is the problem as I did extensive tests in the early days and eventually found an old version of Mach that behaved properly, sadly there were things missing from that version which were lathe specific which I wanted so I had to go back to a newer version. As it was only on the wee Conect 121 lathe that I had the CSMIO on it wasn't an issue as it was just used for messing around. It was however the reason why I never put the CSMIO on the Churchill lathe as often threads with an annular groove were not acceptable for me.
With the SZGH control I have just recently fitted the difference is night and day, everything with it is instant, it just lacks some of the adaptability that Mach can give you.