This is one of those questions where the beauty of mead making shines through (note I said the making part not the beauty of mead itself). Its a never ending chemistry experiment with infinite possible variation due to the wide range of honeys, adjuncts, yeasts, batch sizes, techniques etc. etc.
With that said, you'll find the majority lean towards letting most or all of the fermentation complete in the primary.
Personally, when the lock stops bubbling on a steady consistant basis, I mean like real slow (every couple minutes or less), and there is a well defined layer of the settled yeast on the bottom, if you can see it. I'll take a gravity reading, wait a couple days and take another, if they are the same, it goes into the secondary. Still get some frementation action after that but not much but clearing usually starts pretty rapidly, give it sometime and go into a tertiary/bulk aging vessel.
There are a lot of methods and theories about this, as long as you keep things clean, sanitized and once you start racking/reracking you take precautions not to let too much oxygen get involved then "screwing up" mead isn't easy.
I'm not one to start the cycle of other chemicals, like stabilizing, then sweetening more then wanting it drier so repitch then add more chemicals then cold crash then split, add flavors, need sweeter, restabilize, bottle, bottle pasteurize......
IMHO which is just that, my opinion, don't hold it as anything more than a virtual newb rambling. It's better to figure out what you want the end product to be like, figure out the ingredients you need for it, find a yeast that is going to finish at the sweetness/dryness level you want, let it go til its all done. Keep the ingredients simple and natural, keep the man processed chemicals limited to nutrients if that and keep your experimentations and brewing fun and relaxed...
