"I talked a lot as I usually do" would be most commonly used. If you want to say the opposite, it would be, "I didn't talk as much as I usually do", or "I didn't talk as much as usual". The 2nd one would be common US spoken English.

"I didn't talk as much as I usually did." Using "didn't" after usually would create a double negative sentence. (Meaning it would still be positive and therefore have the opposite meaning of the one you intended) Simile: as ... as ... I haven't been smoking as much as I used to. (Used to... positive. Can't say "didn't used to") I haven't been studying as much as I was/had been (Use positive) The second part has to be positive. If both parts are negative, then the sentence becomes positive. (Also a math concept)