Interesting!
I just finished preping a piece of driftwood myself. I started with a piece that was in the reptile section of the LFS. Found that it takes a lot more than just soaking in hot water over night o get it really prepared. I found that I had to boil it. Fortunately I had an old 30qt stock pot sitting in storage that I could use. I had to boil it several times, like each night for a week and a half. I probably spent a total of 16 - 20 hours boiling this thing.
My consern with using ammonia to draw out the tannic acid likely means that ammonia is likely being drawn up into the wood, and once you put that in your tank, it will take time for the ammonia to leach back out. During that time, it will be like having a bigger bio-load in the tank. But then, depending upon when you add the wood back into the tank, it might mean you don't have to "feed" the tank ammonia for a couple of days, the wood will do it for you.
Unless someone else comes along and can give you more specific information, my educated GUESS is that you should STOP adding "glugs" of ammonia to the wood, and instead keep soaking it in hot water, changing out the water each day. If possible, bring the water to a boil for an hour, then let the water cool over night. Then again change out the water the next day.
The thing I found I was having problems with wasn't the tannic acid (that was coming out easy enough with hot water and water changes). It was getting the wood waterlogged enough to sink. Even after two weeks and hours of boiling, the thickest part of the wood still tried to flip up. So I finally gave up and mounted it to a piece of slate to ensure it would stay down.
Actually, based on my experience, unless you have a piece that is VERY stable (i.e. impossible to "tip" over) you should plan on mounting it to a piece of slate to keep it stable in the tank. I found slate suprizingly easy to drill through. From there I've been told you just need stainless steel screws. I hope brass screws are just as good. When I was ready to mount my, that was the best thing I had on hand.
Goodluck on the driftwood.