My understanding is there are a number of things that have to be right. In addition to rigidity and precision of the machine itself (bushing quality, rod runou

My understanding is there are a number of things that have to be right. In addition to rigidity and precision of the machine itself (bushing quality, rod runout), the speed, layer height, temperature, and filament regularity are all important to quality. There are other software settings that impact quality as well. Bed leveling in a machine that doesn't have software auto-level is another big one. If you know the stepper motor specs you can calculate the resolution. Most motors are 1.8 degrees per step and most controllers use 16 micro steps. If the GT2 pulley is 10 mm diameter, that gives 0.01 mm per micro-step. If the machine is not rigid and precise then you won't get full capability but 0.01 mm is very good and may be more than needed given the capabilities of the plastic, and the layering process.