Yes Jeff, the throw out bearing is always and only revolving when the clutch pedal is depressed.
However, it is my understanding that the true damage to the throw-out bearing is done as it engages and disengages (in the brief period where it accelerates and decelerates), especially if the shaft is not perfectly balanced. Once the bearing is spinning and there is no acceleration force (ie at a stop light), it is quite happy. Therefore, as I understand it, the actual act of pushing the clutch peddle in and out is what does the majority of the damage. Maybe I've been sniffing too much glue.
Old school used to say always leave the clutch out at a light. Nowadays, I think people are more divided about whether it actually does any harm.
At a stop, I don't keep the clutch peddle depressed simply 'cos it means more work for my leg :lol: .
Certainly don't ride the clutch.