The winter leave has been a pretty good deal, take two months off lose only one months pay, so effectively it’s half paid winter leave not unpaid winter leave. It doesn’t generate more standby, if no one had winter leave there would be less flying to spread around between pilots so even more people on standby each day.
I Think the poster who listed winter flying hours was actually an easy jet pilot, if their posting history is anything to go by, hence the high number of hours. My highest was 40h in November and lowest was 8 in January. But that’s on the 737, as has been said there’s a lot of training happening on the airbus so low flying hours in the winter for non trainers. But that’s always been the same if you’re in a base with a lot of training captains, at least on the 737 fleet.