Whenever I make BB, I use Julia Child's recipe, or a variation thereof (like the J&J version). However, some recipes out there recommend marinating the meat first, overnight, in the liquid. What purpose does this serve? Second, I always have issues with the sauce. Once I remove the meat and boil the sauce down, it never really gets as thickish. Does it need to rest for a few minutes after adding the flour, does it thicken if it cools? Also, when is the best time to taste it to see if salt is needed?