Code Review: Does the reviewee have to be present at a peer code review?
A peer code review can be done shoulder to shoulder or pass around via e-mail/TFS. Over the shoulder reviews do require the reviewee to be present and have the benefit of greater information sharing and learning. The drawback is that they can result in scheduling challenges and disruptions.

Pass around code reviews don’t require the reviewee to be present, and thus don’t have the scheduling challenges that shoulder to shoulder reviews have. Also, pass around reviews provide a record of the review without additional overhead.

Quote:
“Tool assisted reviews strike a balance between time invested and ease of implementation.”
– Jason Cohen

Application:
I would recommend performing 80% of code reviews via a tool assisted pass around style of process like the one provided by TFS 2012. The remaining 20% of code reviews should still be tool assisted, but doing the review side by side. Doing this type of mix should maintain the balance between optimal use of time and maximizing learning opportunities.

References
http://smartbear.com/resources/whitepapers/best-kept-secrets-of-peer-code-review