as usual, it depends...
first, there's the amount of time you can devote, but larger factors are the types of hubs you want to write and what your experience and knowledge base is. eg, i use my travel jouernals going back 20-30 years as basis for some of my hubs on travel. these take some time, still, to add mapsm, pix, etc.
much easier to create are recipe hubs, esp'ly since i have so many already written up for my personal use.
in the end, the hubs per day/month, etc is really rather meaningless - what counts more is the quality of what you write, and how many people are interested.
i've been here 3 months & written about 80 hubs