I'm not sure how you mean "maximize". The best way to make Adsense Channels work for you is with new or a re-designed sites. You should give each Adsense placement their own channel, so you'll know where the clicks are coming from. If you have 100s or 1000s of pages, it's impossible to give every page their own channel, so the ad placement channels are the most logical. When it comes to established sites that no longer need tweaking, it is pointless to give the ad placements individual channels. Just use the url channel for these and save the channel space for other, newer sites, or in case you want to experiment.