i've been here about 2 months and published over 60 hubs & agree with the others - to produce a hub a day you need to alreadyhave a good knowledge of your subjects
my hubs revolve around food, travel & history, and i've been doing similar writing for my web pages over the last 15 years. plus i have thousands of photos and my mostly hand-written journals available from our travels.
i've currently got over 100 hubs that i plan to write, and could generate more in a short time. i used to enter a lot of recipe contests, so also have a couple hundred recipes written already
it takes me about 30' to do a recipe hub, and i've spent 3-4 hours creating some of the more detailed travel hubs