In my opinion, other faceting machine features like a larger angle gauge attachment, electronic gadgets, or an attached microscope are useless for serious competition cutting. The coarser laps required to get rid of most of the rough are used to speed the work, The coarser laps are all extremely uneven and not considered with this Stop Method. This whole procedure is done only with the fine cutting and polishing laps. If you find that the stone just touches your moving lap in all areas equally, then you have a very flat lap and your machine is perfectly aligned. But there are always tolerances involved.
Nothing is perfect, or stays that way.
Change does happen. My typemetal lap is the flattest of my collection. My copper 1200 is very good, but noticeably uneven in comparison. In regular cutting with the copper 1200 I am riding up over hills and down into valleys. If I use the angle stop with the copper 1200, I am cutting just on the top of the hills.