Now the question is why use coops in the first place?
Well the biggest plus is the shared cost, being able to make bulk purchases in the leading traffic exchanges mean the members of a traffic coop get their pages shown in top quality exchanges at an affordable cost.
The second advantage is diversification; having ads spread out over multiple exchanges you gain the advantage of greater exposure.
Thirdly, it's a set and forget advertising system. You know your ads are being shown in the very exchanges you want them shown. With out you having to remember to assign credits, you can even slow down your surfing there in order to concentrate on other tasks.
One other big plus is, by using coop's you get a very much higher unique view ratio, adding your page directly to any exchange gives an average unique count of about 60% but with a coop because of the number of sites in rotation the unique count climbs dramatically to around 90%
One last tip, if you are going to use multiple coops, then advertise different URL's in each. Doing this will keep there unique page view ratios intact, In essence if each coop advertises in the same place then while individual coop unique views will be high, in actual fact that percentage will be compromised if you advertise the same URL.
By using a different URL in each coop you preserve that unique count for each URL submitted.
PS: A different URL could just mean a different splash page link for each site you want to promote