I was waiting until this thread degenerated enough to reveal this tip - just so it would not be too embarrassing by comparison. While I feel this point has been reached, I still fear my tactic is not going to be completely successful. Nevertheless, here goes anyway. As my Latin is rusty, I will try to relate this shocking information in as genteel a way as I can, so as to not cause delicate ladies to faint. I am afraid a youtube video is simply out of the question!
A story was related to me, or maybe I read it somewhere, about a certain Zen Roshi who ran a training temple in Japan I think. Anyway, he was a big cheese so he had his own outhouse. Either he died, or more likely one of the students got the job to clean out the outhouse - but somehow it was discovered that this Roshi was so predictable and systematic in his shitting that inside of the outhouse, in the place there the TP was supposed to go, was found a virtually perfect skyscraper of single squares of used toilet paper, all neatly stacked one on top of the other.
Now I'm sure this was supposed to convey some deep truth, but it was lost on me.
However, some time later I realized that (when backpacking) if you neatly fold up your used TP, very soon it becomes a ball and, for a time at least, it maintains a useful radius and, one might say, architectural integrity owing to its properties of construction - an approximation what Mike Clelland might call the "right sized rock". During this period, or "phase of growth" - one can greatly minimize one's use of TP by making use of the ball as a "substitute rock" with just a few additional sheets of TP covering each use. Now keep in mind when properly constructed the used side of the material is always on the interior, where it acts as a kind of cement, while making no actual subsequent contact. The squeamish have the option of adding a few more sheets of TP, after as extra insulation.
Note this method can also be used with natural materials where the rock-substitute/ball can be used as (Mike Clelland's words not mine) a "finisher". No last-minute moss or stone collecting required!
At some point, but usually if one is economical only on a long trip, the radius may grow to be impractical, at which point the process can be started again. The final shape of the "substitute rock" saves space (of course in a zip-lock) as well as TP used, and is easy to drop in the trash or otherwise appropriately disposed of it after a trip, though stealth is recommended in this last step in order to avoid any embarrassing questions or attention.
I'd like to imagine the Roshi nodding sagely to me in approval after hearing about this - as if we shared some secret knowledge. But most likely you all think I'm a nutter. But there you have it, my up-to-now-super-secret (and super-embarrassing) all-true tip/teachings on saving TP weight, and all in accordance with maximal LNT. And a pox upon you if you burn or bury your TP on the trail.