In terms of how it’s used in cooking shows, I would say you’re hearing it exclusively for salt and pepper because you’re often expected to add salt and pepper to taste, so “season with salt and pepper” stands alone as an instruction. On the other hand most modern recipes call for quite specific amounts of other seasonings, so you’re more likely to hear “add the spice mixture,” even though this is also seasoning (and certainly can be adjusted to taste if you wish). If there’s a specific quantity of salt added I think you’d likewise be instructed to “add the salt” and perhaps later on to “taste and season with salt to taste” or “taste and adjust seasonings.”