The Best Length for a podcast
According to an article from Top Rank (which sites Stitcher as the source), the average podcast listener stays connected for 22 minutes on average. This is one of the reasons why including podcasting as part of a long form
content marketing strategy is so powerful. You have the opportunity to build a deep, rich relationship with your target audience. Other science has stated 18 minutes.
Best Day To Release
Maybe it's because of new music being released on Tuesday, but a look at the top 25 podcast in iTunes showed that if you release on a single day, it would be Tuesday. 60% of those shows posted before Wednesday and the top day was Tuesday.
Forty percent of the Top 25 podcasts with a regular posting schedule publish once per week. The next most common frequency is twice per week.
I've always said a podcast should be as long as it needs to be a not a minute more. If you have 15 minutes of content, make your episode 15 minutes. If you have 35, then go 35.