What kind of settings do you ask about? Is it just sort of a sliding scale with your first example at one end and your second example at the other, or are there dimensions to it?

Do you mean that the mechanisms and expectations will be more severe if it's framed as value/harm rather than etiquette? If so, I wasn't intending to reduce the potential seriousness with my phrasing.

Nevertheless, even if there are confidentiality-bearing cost reduction skills which aren't widely applicable outside of this use case, I think they would be useful to know.

Were you mostly referring to the TAP you outlined about having meta-conversations? If so, that's definitely a good start, but I wonder if there's anything else possible.

I've also been working on gaining skills that make me more reliable at keeping things private, and making it lower cost for myself to take on confidential information.

Although we may be able to introduce and encourage good privacy etiquette in smaller groups, I doubt society at large will embrace such etiquette for a long time, if ever. Thus, I am interested to hear more about such skills/techniques to make confidentiality-bearing less costly to myself.

A related concern is that you might be the recipient of information spread by a marytavy, instead of either you or the person transmitting the information to you being the marytavy. This can be tricky because receiving the information N-hand often has a different tone than it does firsthand.

This problem (receiving secrets N-hand) doesn't even need to involve a marytavy, just 1+ unauthorized information transmitters.