I'm trying to figure out how they're calculating that, because the numbers do seem high. Let's take "hemming the slits," which seems straightforward. Let's be very generous and say the slits are 8" deep, requiring 32" of stitching. That would be about 8 stitches per inch, fairly reasonable.
But then there's stitching the collar, four rows. I'm not sure what four rows they mean, but if each row is once along the collar, let's say 17", that would be 68" total, or 44 stitches per inch. If they mean four times around
the collar, that would bring it down to half that, within the realm of possibility at about 20 stitches per inch, but it still sounds quite high, and who would sew around a collar four times? At most, wouldn't you sew it once, turn it, and top stitch, for a total of two times around?
There's also the question of how one counts a "stitch," such as whether each visible length of thread on one side of a back stitch is a stitch, meaning this backstitch ----- would have twice as many stitches as this running stitch - - - - - even though the needle holes would be the same distance apart.
I'm curious how others interpret the descriptions, distances and stitches per inch.