They don't have to be loose, you just don't want them real tight--a light snap is ideal for most.

Strings come in a lot of different sizes, as do serving materials. The problem is, as best I can tell, that catalogs generally carry "one size fits all" strings that will be safe for the heaviest of bows and largest throat nocks.

Tight nocks will rob energy and can affect flight on any bow--most folks don't pull nearly as much weight on trad bows as on compounds, so it the effect of a tight nock shows up more.

Strings seem to be overlooked a lot, even by bowyers, in setting up a bow. A good string can make a noticeable difference in speed and noise.

Chad