I used generic resistors and capacitors for my design, which helped a lot on the front end to speed up my design process. But now that the design is complete and I need to build it, I have to go identify each generic part that's "the same", I.e. same package size and value, and manually add the MPN that I want.

Alternatively I could do this in the BOM export but that info wouldn't be saved for next revision, and parts aren't aggregated in that flow either.