There are many reasons to bypass subnets when using PACache. Sometimes site errors are caused by caching, or important information could not be cached, or the site could hold sensitive information that should not be cached, or simply to direct network traffic.
The best way to bypass a particular subnet is to exclude it from PBR* (Policy-Based Routing).
If this is not possible, it can be bypassed in the policy manager, but it will consume server resources to process traffic.
If the subnet has high traffic, it will end up with an unnecessary waste of resources.
*PBR - is a technique used to make routing decisions based on policies set by network administrators.