In my last post - Why you want as many campaigns per account as possible - I talked about the reasons for wanting to have as many campaigns per account as you could get. I also mentioned that I was going to post on why you may want to not do so. So here it is…

The first reason would be if you give your clients access to their accounts in the search engines, obviously you then only want them to see the campaigns that they’re paying for, so you have to restrict the accounts to only hold campaigns for those companies.

What about for those companies that only want to see regular reporting that you provide to them, either through the search engine reports, or through some other interface that you provide them with? Well, this is the scenario that allows you to campaign stuff your accounts… but hold on, not all of those campaigns can go in the same account. If you have campaigns that are bidding on the same keyword in the same geographic location, and they’re located in the same account, then as far as the search engines are concerned, they’re for the same company, and therefore should ’share the load’ with only one being shown at a time (based on the search engine and any options that you’ve set, this could mean that the ads show on a rotational basis, or that the one with the higher quality score will show up until its budget runs out, then the second ad will display). Placing these ads in different accounts will solve that particular problem (unless they have the same base domain in the URL, in which case it won’t, but that’s another topic).

So there it is, 2 reasons to split your campaigns across multiple accounts. There are more, such as geographical groupings, product groupings, etc, but those are primarily aesthetic or arbitrary reasons, whereas the 2 reasons I detail are for necessity and optimal performance.