I checked the brakes in a Macchi just after touchdown then used aerodynamic braking until approaching the exit taxiway, to discover that they had blown the hydraulic line to one wheel during the test (the line was hanging and fluid was found on the runway). With no fluid I had no brakes, normal or emerg, the barrier was inop, and not enuff runway to get airborne again. Pretty rough ground off the end of the runway, I found.
The back-seater was a fellow QFI and he had the canopy open and my seat pins ready for me when the nose bobbed up after we came to a stop.
The moral? Dunno!