I tend not to write a hub in one sitting. I start it one day, and over the next day or two, I add things, and edit, etc. so it is really hard for me to say.
It takes time to add the photos, the capsules, etc., and edit it.
Plus, even after I publish, I tend to go back and think of things to add.
I find that I am getting faster with practice - I make decisions faster, and generally know what look I prefer on a hub.
I would guess two to four hours as well. I had read some other hubbers take twenty minutes, and thought I was way slow, but from reading the answers here, I guess I am about average.