I remember in the RAAF being made to fly an NDB in the Macchi with no AHs.
Even in the 1950's during an instrument rating renewal in a RAAF Dakota, a mandatory part of the test was a single pilot limited panel, single engine aural null NDB instrument approach. Looking back in time it certainly increased your rate of scan. But really a useless exercise invented by Central Flying School instructors with nothing better to do.