I had 50+ blogs. whether link exchange withing this 50+ blog will sounds better. Whether Google will consider these kind of link xchange for page rank update ?
I believe what joemamma means is are they all distinct and separate domain names? They may show as different domains but are actually sub-domains of one main one. If they are all hosted by the same ISP, this can also be a problem. Google can easily see this and may not value these links as highly because it can see the relationship.
try to excange related niche domains.... it will not increase your main keyword value but will also help you to get page rank....