I cover mine nightly although they are short for now I still wake up without the durag on so I do wind up getting a retwist more frequently than others
Locs tend to collect dust/lint from bedding, shirts and pretty much anywhere else which will get embedded into them over time. Try to keep your hair covered at night to keep it from getting fuzzy and losing moisture. A bonnet or large silk scarf will do. If you use a durag your ends will be exposes and at risked for what I mentioned earlier. Keeping them covered will also keep them neater longer unless you are going for a more unkempted look or don't mind paying for a retwist more often then needed.
Thanks! Your answer is awaiting moderation.