Trying to increasing print surface quality (E3D on Flashforge?)

[Mjolinor]

Bit of arithmetic:

If you have a 13 mm toothed gear then one step is 0.2 mm of filament.
At 1.75 mm diameter that is 0.4912 mm^3 of filament.
With a 0.3 mm nozzle that equates to an extruded length of 1.74 mm per step.

If you are using half micro-stepping then each half step should be 0.869 mm of filament but due to inaccuracies in the half step one will be more than the other.

If your "oscillations" are 1.74 or so period then that is probably the problem.

Attached a picture of something on my printer that seems to show the same thing. The oscillations are just under 2 mm apart so that seems to fit.