I personally find diffraction to be a consideration in my photography. Like many other photographers, my early large format efforts amounted to stopping down the lens to eliminate the need to use the camera movements. That was true because the use of camera movements was daunting to me at the time.
I think that it is worth noting at this time that I am using relatively modern lenses and my goal in their use is to obtain maximum print sharpness and local contrast. I understand that if one is using older lenses or soft focus lenses that what I am about to say will not be applicable.
I think that a great deal depends on the film format, how it is going to be printed, and to what enlargement. If that is involved. Obviously if one is using medium format then movements are not normally available.
Diffraction is a factor of lens opening size to focal length size coupled with the film format size. It is caused by light rays bending at the aperture opening. If the opening is allowed to be of sufficient size the bending of these rays does not become the consideration that it does when the lens is stopped down excessively.
In my photography today, I try to never stop 4X5 down below F32 and ideally I try to keep it at F16-22., On 8X10 and 12X20 I will stop down to the limits of the lens if indicated. In my 4X5 I enlarge the negative typically to 11X14 and occasionally to 16X20 maximum. My 8X10 and 12X20 are contact printed. If I were enlarging 8X10 my fstop limit would be F64. That is because the enlargement factor would not be as great as 4X5. As degree of enlargement increases the effects of diffraction become increasingly apparent.
Since I began living to the parameters I indicated for 4X5, my print sharpness and local contrast have definitely shown an improvement.
The effects of diffraction are one of the links in the chain that will either contribute to or detract from the rendering of a fine print.
I didn't arrive at this criteria by myself. This is information that Howard Bond and others indicate as being a condition of their photography.