If I hadn't been sick this week, I'd be up to 58. NORMALLY, I ski 4 days a week, some days 10 - 2, some days 9 - 5 depending on my mood, conditions, etc.
I'm not advocating no other exercise, but the fact is, I don't. However, my "ski schedule" is rarely more than three days without a day off. I've done five in a row, but I've paced myself and am dragging anyway by day 5.
As for skied vertical vs. lift vertical.... I use a Brunton ADC Summit. The first 13 days this season (normal practice), I made sure that my battery was good by noting the lifts I took and how many runs on each, etc. At the end of the day, the "descent" number was within 1 or 2% of the lift vertical. I don't agree that lift vertical is more accurate, at least here, as we have trails that sort of swoop like roller coasters here and there (i.e., you ski UP for a while and then back down again). So, I skied that "down" vertical twice, right? So, I would expect that the Brunton number would be slightly higher (which it is) depending on how often I was on those particular trails. 1 to 2 % isn't that big a diff anyway.... After all, barometric fluctuations can give you vertical if you spend all day in the bar. But, it's a heck of a lot easier to start the device at the beginning of the day than to keep counting lift rides.
I don't have an iPhone, but a man I know who does and likes gadgets, says that his altimeter watch is WAY more accurate than the iPhone app. Just reporting what I heard...