For over twenty years I shot slides of my B&W prints for shows, galleries, etc., on a copy stand. Worked fine for prints up to 20X24.

I have now replaced the F3 in the copystand with a D80. Then I reduce the resolution to 300ppi for galleries or shows and 72ppi for the web in Photoshop. I do keep three folders on the computer. One for the original shot, one for 300ppi files and one for 72ppi files. It takes a lot of disk space but it's worth it.