In all honesty, there are no shows that I listen to that do not have a regular publication schedule that they stick to.  I do know of some story telling podcasts that only come out once every month and a half or so that are seeing success.  However, that is a completely different animal than we are dealing with when it comes to building a custom podcasting business.  So, for now, I am saying once per week - minimum.

The reason why this is so important to me is the professionalism that it exhibits.  Remember when you are creating a custom podcasting business you are trying to please two distinct groups with each show - your listeners and your future clients.