Some people are very adept with the computer, can type very fast, and can think of lots of things to talk about. I actually churned out 100 hubs in 30 days. Except for the last week when I ran behind and wasn't feeling well, I think that the quality of each of the hubs were really good. Sometimes, the practice and repetition makes you get better faster. You get lots of experience, so you learn quicker.
I also spent less time agonizing on decisions that probably wouldn't matter much in the long run - such as which photo to use or which types of modules to include.
I wasn't working outside the home, and generally spent nine or more hours a day writing hubs. Each hub took about two to three hours each, although a few were faster and a few were slower than that.