The principle is true and follows from the rule that no resource should be idle if there are requests that need it to be processed. Memory, however is seldom t

The principle is true and follows from the rule that no resource should be idle if there are requests that need it to be processed. Memory, however is seldom the bottleneck. This is because most apps are not designed to queue requests if they don't fit in the available memory - they just allocate until they fail. So, unless your apps are designed to queue requests in order to fit them into memory, this principle is probably not the explanation for the high memory usage.