I measure my skiing based on the width of my skis. A day on my 107's is far more valuable than a day on my 78's.
With a Vail pass, my days and vertical are now tracked however for reasons others have noted, I don't compare how much value I get each season from those numbers versus those of other skiers while instead using number of days from a personal perspective of skiing over decades. In other words, my 25 days in 2018 compares only to my numbers of days in previous seasons and not to other skiers. .
We don't consider it a ski day until we've taken 10 chair rides, (though, we have two chairs we only count a 1/2 ride).
Vertical doesn't seem to make much sense to me. At Mt. Baker Chair 5 is mostly an intermediate cruiser. However, the chair takes the straight line from the bottom of the hill, right over the most technical of inbounds skiing at the ski area, a run called "Gabl's." The blue runs go around it, but the double diamond run is a straight line right down the chair line. When I ski the regular cruisers I almost don't feel any "work" to it and when I get to the bottom I'm not ever breathing very hard. When I ski Gabl's I know it big time. My legs burn, my heart rate is way up there, and I'm breathing hard. It's exactly the same vertical and a shorter distance, but a whole lot more skiing.
Because for those who are in to keeping track it just doesn't sound nearly as good in meters.
Speaking as someone who has tracked their vertical since 1989.
It all started when a co-worker said his annual week long trip to Colorado amounted to more skiing than my every single weekend skiing in the Poconos. He said that his 40,000 per day amounted to more skiing than I could get on an 800 foot vertical hill. So, of course, I had to prove him wrong!
I started just with number of runs and vert in a spreadsheet. Added comments about conditions, weather, which runs, with whom, etc. over time, which has actually proved to be quite useful. Then I added which skis I used, and when they were last tuned. Then I added cumulative feet for the prior year for that ski day to help gauge my increasing (or lately, my decreasing) fitness.
Sure the local area tracks my vert. And there was a time my position on the vert list was a huge factor. (My best year ever was number 25 -- the year I slammed into a tree and ended my season. That resulted in a complete rethinking of the competitive aspect.) Relying on the mountain for tracking makes you a bit of a pain when the liftie is feeling lazy, so I do my own tracking. And I've largely let go of that focus on my relative performance to others and mostly look at my performance compared to myself in other years. As I age, that comparison is both upsetting and yet an incentive, depending on my mood.
I realize that's thirty years of what some would call obsessive behavior. But ultimately vertical, not runs or days, is the only way to compare "amount" of skiing. If this was cross country, maybe mileage would make sense. But this is downhill. I've tried hours, but you'd need a stopwatch to eliminate chair time, line time, talk time, etc. It's too exhausting. I just start my altimeter each day in the locker room. Turn it off when I return, then enter that info on my spreadsheet when I get back to the house. Takes about three minutes for all those actions combined. Most of which is the time opening the spreadsheet.