It sure seems like the transmission shifts a little more goofy than normal after 20k or so miles between transmission fluid drains. I had noticed some weirdness (not as extreme as you mentioned) shortly before each change at 30k, 60k and 90k services Afterwards it felt less jittery and no odd TC fluctuations. Seems hard to believe these are that susceptible to "dirty" fluid in only 20k-30k miles, but I don't know what else to call it. I did a drain/fill every 60k miles on my last Nissan and the fluid looked/smelled like new every time. It also never shifted goofy even once in 150k miles. Not sure why transmissions are such a brain tease for Honda but that's been my #1 complaint on this vehicle from the start.