That's the size of it. A good TP can make the bird sit up and sing quite nicely. We line folk are a bit more sedate and that routine precludes a reasonable expectation that we can replicate the practised performance of a TP out to get the best data feasible for the OEM.
Sometimes it goes a bit wrong .. eg let a bit too much sinkrate catch you out at minimum speed and it's all over, Red Rover ... (nearly 40 years ago, now).
Did I mention something about line pilot folks not replicating TP performance landing ? Performance takeoff we reasonably can match but not landing ...