Hoi @musquetier,
Your multi-channel workflow is correct I would think, although, I have 3 remarks:
1) when you have applied flats, the correct vignetting step is not needed, since you should have corrected the vignetting of your data with the flats ? So the correct vignetting function is only needed when the user doesn’t have adequate flats at that moment in time. For instance, the tool can be used for a quick review of your data if you haven’t made flats yet. Or if you are struggling with proper flat correction with really short focal lengths ( less than 200mm).
2) if you need to apply dark frame calibration/correction on your lights due to Fixed Pattern Noise in the dark current (which you have with the asi1600), don’t use bias, the bias is always in the darks, like @mauricetoet indicates as well.
3) Regarding the flats, either subtract a masterbias or subtract a master darkflat (or is it flatdark…) of the same offset and gain as the flats. ?
2) and 3) are both recommended versus applying both bias and dark subtraction.
If you do subtract both bias and dark masters, then always convince yourself that the bias is subtracted from the darks in the masterdark creation, otherwise you subtract twice the bias pedestal which you don’t want to do.