Yes, the middle of the bell curve will always be a medium. It makes things easier from a forecasting standpoint. But it’s also sizing. A medium is the “sample size” - meaning for pre-production, we fit on a medium mannequin and our fit model who wears the early protos is a medium. Sizes scale up and down to complete the run. The further you grade, the weirder proportions can get (if you’ve ever heard plus size women complain about extended sizing like XXXL vs “true plus” at a 3X, they’re totally warranted. A XXXL is a graded out version of a medium body. The 3X measures and builds on a 1X fit model.) As much as we complain about inconsistent sizing across brands, it tends to make a more tailored product for the target demographic.
The reason you see a lot of fringe sizes left on the rack mid to late season is due to forecast standard deviations and maybe case pack rounding. In stats, population size and standard deviation have an inverse relationship. There are a lot of mediums, so we tend to have better and more consistent forecast inputs for that size. Very small, very large, or short / long inseam pants are smaller numbers, less consistent, and they’re either gone by January or sold for 60% off the next summer. It’s the same reason you see boring colors in extended sizes and variated inseams - sizing is less consistent, so we go with consistent, dependable selling colors so we don’t end up with 2 eons of supply on hand. (And that gets even more important if it’s a “true” short built on a short model vs just a shortened inseam. Factories and brands see that as a separate style that needs to hit factory mins and meet brand profitability thresholds all on its own).
The US is big for skiing, but Europe overall tends to be stronger, so global brands tend to split the difference on fit (we in the US tend to be a bit shorter, and on the women's side, more hourglass shaped). I’d expect to see more short inseam sizes as the Asian ski market grows and supply chains get more creative on how to reduce minimums.
