When would you apply QoS to Nexus system context and to normal interfaces?

Hi, after going through Ciscos Nexus QoS documentation it tells you WHERE you can apply the different class policy maps to but it doesn't necessarily TELL you why you would want to use one method over the other.

The main reasons why I could think you'd split the 2 would granularity. You'd apply a policy to the system-qos context if you want everything affected in the sameway and you'd use individual interfaces in the same way, if you needed a particular queue size, bandwidth or qos-group mapping on one interface for a CoS value but not the same on another then you'd go with the interface method?

Am I right in assuming that is the only different between applying a QoS policy via the system qos context and on the interface level to?

Cheers