I'm all for precision when possible, but those words exist because there are times when people haven't counted, and maybe _can't_ count, for example, at some time in the near future, but you don't know exactly when conditions will be right (getting something finished?) "a few days", "several days", "a couple of days" (maybe two days, maybe one or three). When you have objects, you can usually _see_ one, two, three, four, but five or more you don't necessarily count, because you just got a quick glimpse. Even fewer than five, something like chickens or cats moving around in brush or high grass, if they're all the same color. Or if you remember doing something in the relatively recent past, but you really don't know how many days, or remember which day of the week it was. That set of words is _deliberately_ imprecise words, that gives the approximate idea of how many: for example, you wouldn't say "a couple" if there were at least ten things, but they might be "a few", depending on context, like comparing a small group of cattle to a huge herd of cattle.