If I recall correctly, ship with pinger locator actually drops a test ULB
Yes, but it is good practice to deploy the beacon with a flotation collar and an acoustic release to recover the device when the calibration runs are completed. Else to recover the beacon with an ROV on a test dip.
The Party Chief is under immense and most insistent pressure from the client reps, eg the accident investigators and the interested partners such as the airline and the manufacturers, to get on with producing line kilometres and square kilometres of searched seabed. Those guys tend not to understand the importance of prelim work such as measuring the temperature/salinity profile of the water column and calibrating the signal strength characteristics of the hydrophone in the ambient conditions. They just want you to get on with the search. Therefore it is sometimes necessary, under protest, to skip the preliminaries and start knocking out the mileage to satisfy the men who are paying the dayrate.