In the context of WAAS using WCCP services 61 and 62...
Generally speaking at the branch 61 is placed on the LAN and 62 is placed on the WAN facing interfaces.
In the Core / DC it is reversed 62 on LAN and 61 on the WAN.
61 hashes on source IP and 62 hashes on destination.
Hence in typical branch to DC / hub and spoke type deployments this is the most common placement of WCCP services.
Both are redirect in statements as well (e.g. ip wccp 61 redirect in). Now, you may have other WCCP services or a specific configuration reason to use redirect out (e.g. maybe you have DMVPN deployment).
For a good guide see this validated design document:
http://www.cisco.com/en/US/docs/solutions/SBA/February2013/Cisco_SBA_BN_ApplicationOptimizationDeploymentGuide-Feb2013.pdf
