As I understand it, filament manufacturers fan speed only applies to the part cooling fan. You still need the fan for the heat break / cool end of the extruder to prevent heat creep and blockages.
The speed settings are a ‘workable range’ which apply to print movements only. I generally run calibrations on filaments that I haven’t used before especially for flow ratio & volumetric speed. Travel maximum speed is limited to the physical maximum of the motors regardless of the speed setting in travel speed and acceleration.
With Bambu filaments I tend to stick with the preset values but with 3rd party filaments I do a range of calibration prints ranging from temp towers to the aforementioned flow rate and volumetric speed. Some of the calibration is found in Bambu Studio, Orcal slicer has the same + more or you can find calibration tests on the internet - a good place to start is Teaching Tech.