The key really is to write as many QUALITY hubs as you can without comparing yourself to others. It depends on how much you can do and how much time you have. The number of hubs you publish varies depending on a variety of factors:
How long does it take?
1. How fast can you think of new topics to write about?
2. How quickly can you do the research, gather the images, etc.
3. How fast can you form the words to write a quality hub?
4. how fast do you type?
how much time do you have?
I try to publish as many hubs as possible while keeping them at a high quality. I have written as fast as 100 hubs in 30 days and as slow as a handful hubs in a month. When I wasn't working outside the home, I made HubPages my full time job. When I am working outside the home, HubPages sometimes is a part time job, and other times it gets to be a temporary job that has to wait. Some weeks, I haven't published a single hub.
My average is about 7 hubs a week, but it is skewed because of the 100/30 challenge. Not counting that month, my normal average is generally 2 or 3 hubs a week.