The safest bet would be to aim for flank acc cap, yeah; if you're going to be forced to be in-front of a boss-type enemy for any substantial amount of time you would want to hit that acc cap as well, but I'm sure that difference could be made up with food.
edit: My reasoning behind going for flank acc cap is not only for HT, but dodging boss mechanics will push you into that area for a considerable length of time through out most fights.
