That is not calibrating anything at all, it's just another way to match the existing calibration that can not be changed.
It's only adding more POTs in parallel with the existing one, where you can change the value of them, to get the voltage divider value for center to closer match the original calibrated value. It only gets 'rid' of stick drift while it's installed, and saying it does it forever is a stretch since the stick will still wear and get out of spec and need replaced again at some point where again that POT board would also need to be adjusted again.