Whenever any technology claims a particular number as throughput, it is considered w.r.t to end user. It is about end user who experiences the better throughput in terms of better service response. When the data is pushed to any system with a particular rate and the data rate end user receive, the difference shows the performance of a system.
If you are pumping data with x bits/second and you are getting x bits/second at UE then your system is not a bottle neck but sometimes the same level of throughput is not achieved.
As per my experience, data throughput is tested at each node individually and when end to end system is integrated it is verified end to end.