I think it needs to be made into a trend that gets widespread adoption among makers and that will hopefully translate into downloaders getting on board. I think people will come to appreciate it because it will save them spending a lot of time and money on failed prints.
Maybe @BambuLab @MakerWorld can make some efforts to popularize the idea on MakerWorld. It will fit in well with their concept of easy one touch printing.
If the fitting test part is one standard part for all MakerWorld, then there shouldn’t be a need for a 1/2/3 size version for models. Once people have their filaments dialed in to properly print the standardized test fit model, then at least in theory, they should be able to just print any future model without reprinting the standardized model.