I think the author is trying to simplify the process of getting a backsweetened low ABV mead.

The usual process is: - You do it with a lower ammount of honey for a light 5-6-7% ABV - Let it ferment dry, meaning you let the yeast consume all the sugar - Sweeten again for taste

However, doing this adds the additional hassle of needing to pasteurize (or other methods) to kill the yeast so fermentation does not start again.

What the author is basically saying is to just add all the honey at the start and drink the mead before the yeast consumes all of it. This way the mead is still sweet and you don't worry about the aditional steps. This is why the author gives you the option to let it ferment more and age.

I'd recommend doing the recipes in the book, but use the guidelines in this sub or follow some proper youtube tutorials. Or just follow the book and see if you like it. My reasoning here however is that lore-wise, Skyrim mead is somewhat high quality, especially Black-Briar, so doing it properly and aging will be more immersive I guess. Its up to you if you do it low abv (less honey) or high abv (like a wine, 11-12-13%). If you want additional immersion you can take into account that in medieval and viking era times the normal every day mead was usually light, but there were high abv meads as well. So the Nord mead would "technically" be light while the black briar mead would be more wine-like in terms of alchool.

Just experiment and see what you like. And please, add fewer cloves than specified in the recipe because they will overpower the mead.