It is pretty much a guarantee when I listen to a 99% Invisible episode that I'll have no prior knowledge of the topic and by the end I'll be intrigued by it and even feel like I somehow now have the authority to speak to the topic. Personally, 99% Invisible episodes are the perfect length. Majority of the podcasts out there are an hour or longer. I usually have to break each of those up into two or three listening sessions due to my commute and schedule. Most of 99% Invisible episodes are around 20 to 30 minutes. Usually I can finish them in one setting and it's just a much more gratifying experience.