It's also better to be too short than too long when starting a podcast. When or if it ever gets popular and people become devoted to it we can have 2+ hour long podcasts, but until then I can't imagine many people actually listening to it.
Also not imposing limitations & organization is the best way to have real quality flowing conversations. Coming up with a few base subjects beforehand is good, but basing it entirely on doing 10 unspecific general ideas without deciding together what we want to address beforehand is bad. Generalized segments lead to us either not having much unified interest in addressing a topic, or each of us wanting to tackle different topics that the others aren't aware of or don't care about.
If we are going to have general topics we have to at least tell each other what we want to talk about [relating to the topics] beforehand.