It seems to me that if one wants to eliminate confusion, describing a seating length by how much longer than touch it is, in thousandths, and how touch was determined is a good approach.
My chosen touch reference is the one that Alex Wheeler uses that is described in a video on this page.
https://www.wheeleraccuracy.com/videos
So, this is how it would go. "I seat my bullets .008 longer than touch, as found by the Wheeler method."
My knowledge of the original, pre internet use of the word "jam" when describing bullet seating goes back to early black and white issues of Precision Shooting, and conversations with top short range group competitors.
The way that they did it (and I still do) is to seat a bullet long enough that it will be pushed back as the round or dummy round is chambered. This involves measuring the length before chambering to make sure that it is shortened by being chambered.
The case must be at the same neck tension, thickness and state of work hardening, as well as interior finish condition as the round will be loaded for shooting. The resultant measurement is specific to those conditions. This was usually done at the range, as part of load development loading there.
Back then, if I was asked about my seating depth, my reply would be something like, I am seating three off jam (meaning three thousandths shorter than jam).
One hall of fame shooter that I know would even refer to things like twenty off jam, even though, with the ogive numbers we were using that was likely slightly jumped.
There are lots of ways to describe how one is seating, but for me the most important thing is to not be ambiguous. These days, I would refer to thousandths longer than touch, or thousandths into the lands, but at the same time I would have determeined jam so that I would know the range that I had to work with between touch and jam.
Generally, with the powder that I have shot the most (133), I have found no advantage in seating at jam or longer and letting the bullet be pushed back as it is chambered, but for the second most popular 6PPC powder (which I believe to be LT32) I know some do well that way.
