[commandar]

Using SI doesn't mean you shouldn't maintain consistency between units you're actively comparing to avoid inadvertent conversion error. If your working units are mg, using mg across the board is completely sensible. It lowers the mental load involved and reduces the chance of the human factor introducing errors.

It has nothing to do with being uncomfortable with working with SI units and everything to do with having a consistent working environment for me.

For example, If I were drawing something up in CAD and needed a particular face to be 120mm, I'm completely aware that could be represented as 12cm, but I want the software to label that as 120mm so that it's consistent with e.g., a 23mm face next to it.

Your working units for sodium in food consumption are milligrams. Labeling the final sum the same way is a good thing.

[DanBC]

Sure, but say 6000 mg, don't say 6k mg.

[commandar]

That'd be ideal, yes, but I'll take 6k mg over 6g when mg are the working units every time. The k makes it much more explicit that there was a shift in magnitude than just silently converting between units.

[namibj]

Yes, but if the face is 1200mm, you do see it as 1.2 m. I rarely like the intermediate units (1e1, 1e2, 1e-1, 1e-2), as they feel like bikeshedding.