I know of at least one PAX (not me) who flew the CX to get (eventually, and super non-direct, I might add) to Ireland. One body isn't much. But obviously, it happens. A quick stop in YYT is still superior to routing through YYZ, as someone in YHZ would otherwise do.
I don't know enough about O&G to know if (or why) their loads would go up in winter. But sure, why not. Or maybe frozen Newfs vacay in the UK or Europe. There is a demand, AC updates the sched and equipment to meet it. Amazing! (?)
WS "scissoring" flights through YYT to Europe has been a thing for a long time, year round, I believe.