I think this one is for @ogiewon
I don't know if this is accurate, but I have an EasyStart soft-starter (link below) for my heat-pump, so I can power it using a portable generator when power is out:
It comes with a phone app that records the line frequency, the live current, and the peak starting current draw.
First time the heat-pump ran after I installed it, it measured the line frequency as 59.9 Hz:
After about 5-10 starts, it measured the line freq at 59.8 Hz and has stayed there.
I just use my IoTaWatt home power/energy monitoring device to monitor voltage and frequency, along with power usage.
Perhaps life is just a bit slower in Louisiana.