I heard that google only allows three adsense blocks per page. Well, what if you have a blog with four posts on the main page, each with one adsense block in it? Does this apply? I made four blog posts and suddenly the adsense block in the first post went MIA. However, when you click on the post and go into it, the adsense block appears.
3 content, 2 search and up to 3 referral blocks PER visible page. If you have one content ad in each post and show 3 per page you can NOT have more in frames, columns or anywhere else on that 'page' D
Google allows up to 3 ad units per page. Obviously, you can place more but only three of them will show the ads