Depending on the kind of blogs you're publishing, I'd say that, typically speaking, you could set between 5-10 blogs per page to maintain a great loading levels between each pages. However, if your RSS content uses images, with the text you're publishing, I'd consider keeping the minimum value, since - without knowing how many times your blogs could be changed - it would require re-downloading some new images at the same time (also depending on the mount of users you might have everyday - which could increase bandwidth).
