If you have accounted for 'all' the differences on the grid, the GLA adjustment should be only 1 number across. If you have a GLA adjustment tier, you got the wrong comps, or missed an adjustment for some other difference. If i saw that as a reviewer i would look for a good explanation. Unfortunately no, CU will go crazy with different GLA adjustments. CU looks at what all the other appraisers do, and they don't do what you just did. So it will ding you, and i agree with it. You will get a higher bad grade CU score. So beat your head against the wall everytime you do that, cause it will be dinged wrong each time. Not a smart business decision.
As a past r.e. broker, you even have my selling head confused with you thought here. A sliding scale involves more than 1 point of reference, and we currently have nothing to prove that, or even explain why there is. Buyers don't use a sliding scale, they buy the hot buttons. In being too precise, you open yourself to be proven not an expert.