I have seen quite a few people mention not using the magneto speed for load testing because it affects barrel timing.
Is there anything wrong with using it for load development and just planning to use it all the time? As long as it's consistent why not just leave it on all the time?
I do this, for me it works I have not noticed a different in group size with my rifle only a poi shift up. I seat it up against my muzzle brake so that it is in the same spot every time. The points about how tight it is are valid I'm sure I just do my best to tighten it to the same amount every time hasn't been an issue for me. I like to have all the data from it.