The more I think about my use the more I realize the limitations of what iTunes gives me for content. It really biases listening to the high volume, serialized program that I would call my must listens (TWIT, MacOSKen, Woot). The >90% listen end to end.
I tollerate iTunes with large multi-program feeds like ITConversations because I consider it high quality so the 'noise' of extra programs isn't critical. The only filter I ever apply to this is maybe the odd skip or 'mark as read' when I get behind.
The next tier is when it starts to get interesting and iTunes becomes problematic. There are a number of feeds that are largely single programs or small collections that I listen to some but not all. Frequently barely 50% of them. (NPR, CBC, BBC, EdTechTalk, This week in Law) There is value there but the noise starts to get pretty high. I've subscribed and unsubscribed to these feeds several times (currently CBC and TWIL are in, NPR, BBC are out, and I just readded EdTechTalk). I want to 'pay attention' but I also need to filter before it gets to my ears. For any given period I might listen to 40-80% of the shows in the feed.
Then there are the real outliers the <20%, they hang around mostly because they are relatively low volume (2600, TMUP, and a local public affairs show called PublicEyeOnline). These are <1 wk. The ones that are more frequent I probably dropped and don't even remember anymore.
I started to use smart playlists in itunes to take the podcasts and create situational playlists (workout, walk to work, listen to while waiting for X, bored on couch- Mac Mini/AppleTV) not very successfully. This is both event (commute, travel, bored) and location driven (iPhone, AppleTV, Mac Mini on home Theatre, Laptop, Desktop)