Only when its cold and windy as fuck...wind chill is one of our worst enemies. This is also when having a baggier jacket comes in handy because if not you might have issues fitting your hood over the helmet.
I only use it on the lift though. Ive never really liked riding with the hood on, screws with my periph's.
Agree with that. Personally hate riding with the hood up - it either interferes with my field of view or (if I cinch it tight) feels like it restricts my head movement.
Only use the hood on the lift.
On cold and windy days I ride with a balaclava underneath my helmet to avoid any exposed spots.