The site seems pretty valid for that upper east side wall... as for skiing it's very similar to Nosedive, Bypass, Kitchen Wall, Bypass Chutes, Nosedive Glades, etc. The stake is nailed to that Birch tree. It is in a cold pocket facing northeast (much like the ski terrain in that area that holds snow so well and so long into the spring). It is right off the Toll Road, literally just like 10 yards or less from the road surface.
The value in the Mansfield Stake though isn't the depth itself. I mean there's really nothing to compare it to on other mountains or even on Mansfield itself. So it's not something that can be used as a comparison to other areas, so in that regard the siting honestly doesn't mean that much to people. It's hard to say if it's right or wrong, but it seems representative of that area of the mountain. And it's well known to the local ski community because you pass it on your way up the Toll Road to steep back/side country terrain.
The true value though is from it's period of record and it's consistency to compare to its own readings over time. Whether the siting is right or wrong, it's consistently right or wrong. Having depths from 1954 onward, gives it real value as a comparison to itself. And since it's been around for so long, skiers and riders know what the values mean. That's why we have so many benchmarks for ski terrain... at 25" you might be able to wander into some low angle woods very tentatively. At 40" the glades are generally skiable. At 60" most everything is skiable and in good shape depth wise. At 80-100" all of the big backcountry lines are full to go like the "Hundred Inch Chute". Things like that are even named based on the depth the stake is at when it's skiable.