Auto Sensor Clean Function?

What exactly does this do? Should I use it now and then, or just when I notice a possible "dirty" sensor? Is there an advantage to turning on the auto clean when power on/off? Thanks in advance

It gives the sensor a little shake to remove any loose dust.
I always leave it set to on so it works when powering on and off.

It sends a high frequency vibration through the filter stack to loosen any dust sitting on the sensor. Works best if you let gravity help, so do it with your camera pointed down, or at least forward. Not really effective for stuff that's been there for a while, but it's something.

Helps if you also store your gear lens facing down, or at least having the sensor vertical. Never leave the camera lying on its back unless you want gravity to do its work inside.

It's not as good as a puff of air between lens changes. But really it doesn't hurt so why not? My Nikons are set to clean on start up and shut down.

Thanks