Please help me to further understand custom channels. As Google says it is a way to map your ads, but I still have a few questions:

• Is it correct that a single custom channel per 1 ad is not very useful, since you can specify Ad blocks in the AdSense reports?

• I have multiple Ads in multiple custom channels. After this I created 1 custom channel and added all the ads to it. I made this channel targetable, so people can target through this channel on all ads at once. Is this a good way to do it? In other words, is it possible to have ads in multiple custom channels (without targeting, just for analyzing) and then create 1 custom channel with targeting that embraces all the (desired) ads?

• Why is it not possible for me to analyze custom channels (or ad blocks & formats) per site in the Adsense (reports). Or am I doing something wrong? If not, I have to create different custom channels per site to see how certain ads are doing on a site level?