Hehe there's 1 disadvantage, really minor:
Since you don't turn in BH2 and BH3 on first day, you lose some exp you could gain, during stacking.
Of course, gains in terms of saved time and other, are much bigger.
Also, for those who are lazy to read whole above guide, there's simpler guide which I heard from my friend. It is so easy that you can even remember it:
Never turn in BH the same day you taken it
Yes, this way you lose even more exp when stacking, but it is really easy to remember and do. And also you don't have to go to Archosaur after you finish BH.
My BH day looks like:
1. Go kill BH bosses, if I was too lazy to do that yesterday
2. Turn in all BHs
3. Take new BHs immediately (within 30 minutes, but I see no point in waiting since I'm already at NPC)
4. Go kill BH bosses if I'm not too lazy/sleepy/drunk
And one more point which explains why I can turn in and take BHs in any state: it is convenient to place NPC dialog so that first line of it is crossing BH NPC. Then you can put cursor at the crossing, hold shift, and click a lot of times without thinking - your every hit will be either on NPC or on "Quests" or on first quest in dialog. Whether it is "turn in" or "take" quest, doesn't matter, because I have to do both.