As I said before, shooting socks are typically made a bit longer than kilt hose. The only brand I can speak from intimate experience on is House of Cheviot. Their popular Lewis style are kilt hose, and made to be kilt hose. The very similar Rannoch style, on the other hand, are made as shooting socks (which is the lion's share of their business). If you compare the two, the additional length of the shooting sock is incorporated into the band of ribbing between the patterned cuff (turn over) and the leg of the sock. Here's a photo to illustrate.

(The grid lines in the photo are 1" squares).

This is a pair claret Lewis hose next to a pair of brick red Rannoch hose. I've lined up the tops of both. You can see the line of stitching where the cuff is joined to the sock. The sock length is the same -- the extra length is in the cuff, but not the decorative patterned part.

So someone with shorter legs will have a harder time getting the Rannoch hose to the proper height below their knee, but as Jock Scot has said, a simple double fold will fix the problem easily. In fact, it's much easier to deal with the problem of too-long hose than too-short hose! So that makes shooting socks very adaptable as Highland kilt socks.

The length of the cuff (turn over) itself I don't think really matters. There is no set width of kilt hose cuffs, after all. How wide your cuffs are depends on what you like (especially true if you are having your hose hand knit). Some patterns will demand a wider or more narrow turn over. Diced hose, for example, typically have a very narrow cuff, whereas Argyle hose have a wider cuff, necessary to show the diamond pattern. The hose being worn in the above photo by Prince Charles are not repurposed shooting socks, but kilt hose, made as such. He has all his kilt hose hand knit for him, so doubtless they were made exactly how he wanted them to be.

The way most plain colored kilt hose are made, the width of the cuff when worn depends on the length of the wearer's leg, by my observation (and how much the hose have shrunk in the wash). People just turn down the cuff where it suits them, or where they are able to. With a patterned cuff, it's a little more obvious where it is supposed to turn down, but even then you have some wiggle room.