Mythos 2 issues

Hi everyone
Please help
We use Mythos 2 and can not understand how setting “descending weight” (it has two options enable/disable) does affect grinder work?

What is the reachable tolerance for this grinder. We’ve just got -0/+0.2 g (18g dose, 900 rpm, ramp start -3.8) is ok? We’d like to get better result - is it possible?