Average flight time of that prototype is around 2 hours per flight.
The duration of an experimental test flight depends on its general goals and detailed test plan.
Each hour of experimental test flight generates thousands of parameters which undergo data reduction and analysis. Hundreds of parameters are followed in real time. All parameters are analyzed after each flight, some must be completed before the next flight, by dozens of engineers of the aircraftmanufacturer and sub-contractors, GE in this case. Part of the analysis is automated, but most is reviewed by the engineers.