I tried carrying out my TP for a quite a while on one long trip. My hiking partner at the time sort of challenged me on it, asking why I was doing it. I scratched my head and mumbled something about it being part of LNT ethics and so on, but in fact couldn't defend what I was doing really. On reflection, we started to think that maybe it's for people who don't dig their cathole deep enough so that the TP ends up surfacing somehow, and/or for women who use TP in situations where a hole isn't dug.

I've seen people burn theirs (literally seen the glow in the distance before they came back to camp), but I think this isn't a safe long term practice in many situations. My process these days is to just make sure that I take the time and pick a location where I can dig my cathole plenty deep.

In terms of problems with the plastic sack in carrying used TP, my own experience was that just a couple of layers of plastic didn't seem enough to keep the smell completely contained. Particularly in hot weather (?). I'm not sure how many (yes, freezer bag type) ziplocks would be enough to be really odor free when carrying around multiple days worth. Mind you, the average hiker can smell pretty strongly anyway, but there are smells and then there are smells. If you catch my 'drift'.

Might be enough to get a person using smooth rocks and pine cones and snow and so forth on a regular basis. But I have yet to hear a really compelling argument against just burying it deep enough.

We don't ever see how deep other people dig when they feel the urge, but somewhat unscientifically, judging by how well the average bear bag seems to be hung relative to the "4' out, 10' up" rule of thumb, I'm not optimistic about how deep the typical cathole is dug.