Weekly is pretty frequent. I aim for about every 2 weeks and am happy with 3. I find that, by finding interesting guests who can improvise and speak off the cuff, doing some prep, and keeping things to about 20 minutes it's doable. Then, it's also sort of part of my day job so spending an hour or so per week on it isn't a big deal.
Every time I do a developer workshop at work I want to do my best, but dang it takes me a good month of my spare time to get something I feel is worthy of consuming someone else's time.
I just have a difficult time thinking how I'd do a weekly podcast and keep it interesting on topic! But I'm sure there are plenty of people better at this than I am hehe.. At the end of the day though I'm probably happier people keep producing even if I don't consume it all, just nice to know its there