There's been people who have spent over 300 hours/month. Joker2 played 395 hours playing tour 103... 395 hours! He had several tours in the high 200's as well.
But you also never know if some people do share the same account, even though it's not allowed. But Father/Son flying on same computer is happening for sure and can explain some very high numbers.
My own record is at 235 hrs, but I found that to be extremely exhausting and it had a negative impact on my life, even though I'm not working for a living and don't have a large family to care for. Nowadays I'm "only" playing for ~120 hrs per tour.
What makes me wonder isn't how much people are playing.. it's the fact that the "constant complainers" (you know, those guys always blaming everyone for not winning the war, not porking enemy fields an generally wasting resources) are mostly people playing several hours each day. Some guys really seem to confuse a game that you
can play if you want to with
going to work, whether you like it or not.