Just thinking this reading all the brand names coming through. if your doing stuff then fine but if your just sitting still its a bigger problem by far.
Motorcyclists have to deal with far greater extremes of low temperatures than most just sitting still riding a bike ...Like a 70mph ride at freezing point is producing a wind chill of -35 and at a few degrees below that it can drop as far as -50 ...wind and draughts suck heat energy from you so quickly its pointless trying to layer up to keep warm if you can't keep the draughts out.
I always carry a woolen neck tube, summer and winter, and I've a few spare ones tucked under seats just in case I forget, ...on colder nights is just enogh to block the cold air rushing under my leathers via my neck, such a simple item of clothing makes all the difference between just a bit cold, to painfully frozen, oh my marrow hurts!!. ..hours after getting home, real bad I can tell you.
Another bikers favourite tricks when caught in the cold unprepared is to buy several newspapers, and stuff the layers of pages all over your frontal area, feet hands and all .... Saved my life a few times.