RhinoFish - 3:38 pm on Oct 19, 2011 (gmt 0)
keep in mind that it's also in G's interest to offer good targeting solutions, both for them and those they serve. so G algorithmically figures out what to show me in the placement tool - i often see both relevant domains listed, then relevant channels within that domain as well. so i don't think you limit yourself by setting up channels, you add specialty targeting, while your broader (entire domain) remains as well. and since many times, contextual targeting isn't ideal (see my kiss example above), channels give advertisers another relevant, targeted method to use.
what i mean there is that we can combine MANY methods - placements, audiences, interests, remarketing, topics, contextual / keyword, placements... so the picture is very complex already, and any examples are simplifications of what we're doing on our end.
the goal for us both is effective targeting - if you overdue your channels, it won't help you, quantity doesn't equal effective. but, if you have a subsection that you can additionally tag and identify for us, you should attract more bees to that cell in your honey comb hive.
if i had a site about boats, and it was divided into sail and motor, i'd definitely add those as channels.
if i had a site about psychics, i might have a tarot channel... and a channeling channel. :-)