This is true for the boosted lights I sent you but it depends on the converter IC used. 3rd entry here
The Boost IC has an Ultrasonic mode, at light load it decreases the switching frequency but never below 23kHz, typically 30kHz, this doesn’t save as much power as if it had no lower limit, but it guarantees no visible or audible artefacts.
But in my buck drivers it goes pretty low at zero load, around 100Hz, I usually increase it by adding a dummy load resistor, sacrificing a bit of power (not much, like 100-200uA) in exchange for higher frequency.
3 Thanks