I'm going to play the heretic here.
I don't think that checking everything on the ground glass to ensure it is visibly sharp enough is always practical nor possible.
Yes, in the best-case scenario, we'd be able to examine our perfectly-placed and finely-ground viewing screens at taking aperture and with a high-powered loupe that matched the magnification of the largest print we were ever going to make from the resulting exposure.
That is simply not easy to do a lot of the time. Stopping down to f/32 in a dark slot canyon and then trying to wrestle a 10x loupe into a corner of the ground glass to see if the texture on that smooth sandstone wall is still sharp enough for a 16x20 enlargement from a 4x5 negative is an exercise in futility. The same for a dimly-lit interior that requires a lot of depth of field.
I also routinely run into situations where dealing directly with image on the ground glass is less than comfortable. Imagine your camera perched on a cliff side; you've managed to prop up the tripod legs with rocks or whatever to get the optimum camera position, but where you have to stand allows no easy view to the whole ground glass; the camera is off to the side and a little too high for easy viewing and your footing on the loose rock on the slope is rather precarious. Am I going to stop down and check every object in the scene to see if it's sharp enough, or am I going to focus roughly near-far and use my table? That's a no-brainer.
Or when it's raining and dark, and the wind is blowing and there's changing light and you have to hurry, etc., etc. In these and many other cases, I'm really happy I have my table of optimum f-stops for different focus spreads with me. I've used it for years and am confident that my near-far focus points will be rendered acceptably sharp in the final print. Things between the focus points are even better.
Plus, using the near-far method doesn't mean you aren't positioning the plane of sharp focus precisely where you want it; careful selection of focus points ensures that the sharpest part of the image is where you want it to be.
The more I photograph, the less time I spend mulling over the image on the ground glass. I spend much more time selecting camera position, imagining where I want to place the plane of sharp focus, choosing focus points and finding borders for the image I'm making. After that work is done in my head, it's a simple matter of setting up, choosing the lens in my kit that most optimally gets my imagined image on the film, applying movements if needed and focusing (near-far to my pre-determined points). Then, I'm done with the ground glass.
Best,
Doremus
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