If a scale repeats, and comes to zero reliably, no matter how the load is applied, if you stick with one scale for all of your charge weighing, minor lack of linearality, or accuracy is not a problem, but I would note it somewhere in my load notes, what scale, and what the issues are. One of the ways that I commonly test a scale, particularly a digital one, but also for balance beam, is to weigh the same thing repeatedly. If a scale passes this test, I can work with it. As long as a setting gives me the same thing every time, I am good to go. One think that I have noticed is that long range benchrest criteria for charge weights seems to have been picked up by people who seem to have much larger issues, or are shooting sports where that degree of resolution is not important.