You must lead sufficient contents or posts on every page and category. In total, you should have 15-30 blog posts on your whole blog. This is not an official declaration. But, I recommend everybody to at least have it. So, you should have at least 3-4 posts in every category, tag and page. Google Adsense told that we must have sufficient contents in every single web page. So, we should add contents in all pages and categories. There shouldn’t be any blank page without any content. And these posts have to pass the minimum length of 500-600 words as it is the best blog post length. The more you increase the length, the more you go towards to get Google Adsense approval