I have several loads for revolvers that are simply not commercially available. That may be a bit off the track of this thread, but they are specific loads for the function of those guns.
I load for a number of 1st World War rifles. They are military issued rifles and soldiers fired the 'issue' ammunition, not specificly 'fitted' ammunition in those rifles. So I work up a load to the original claimed performance levels and use that in all the 'issue' rifles of that caliber. All seem to be adequate for enemies of the realm out to three hundred yards (or the equivalent in meters, arshins, schritt, whatever).
Most handguns are quite happy to shoot almost any interchangeably. All the .45 ACP pistols I have shoot hardball (or equivalent) well enough to make a 'head shot' out to 25 yards or so (50 yards when my eyes worked better). Except for one target pistol set up for wadcutter level loads only. I have to load that one individually (a 'powder puff' 200 grain lead SWC).
Some hunting type rifles have specific loads, some for more than one bullet weight. Probably more accuracy than is needed, but it suits my OCD.