Sure it can. DoF scales and calculators are only a guide that lets you visualize the DoF in a scene. You can even make your own CoC if that gives you a better way to see it--I know a few folks that choose the DoF index one stop open than the set aperture because they find it meets their expectations better.
Knowing what you get at certain stops on the scale is just a matter of getting acquainted with the equipment. It doesn't matter if it's perfect as long as it's consistent, meaning it's pretty easy to stop down one or two stops extra vs what the scale says. Not only that, but because the scale is consistent it's pretty easy to directly map that value to a diffraction-optimal one. It turns out the crossover between stopping down and diffraction is purely f-stop related, and unaffected by focal length. Here's the scale I had taped onto my Mamiya 7:
Basically, if the lens scale says f/5.6, stop down to f/16. But this is on 6x7; on 35mm f/5.6 would map to f/8-11 approximately. Maybe f/8.5. (.5 indicating a half-stop, so effectively f/11)
But it really comes down to knowing the equipment and how to use it effectively.
Unfortunately the DoF scales on modern lenses suck.
Of course, this assumes a lens that doesn't need to be stopped down further to perform. Those sometimes have their places as well, but in that case I'd just stop down the lens to f/11 or whatever it needs to do well.