Template:Onworld and offworld negotiation
The same dynamic exists in a negotiation. The JC snookered himself into using a four box quadrant to illustrate this, because there are two perpendicular axes at play here: How many people are you speaking to, and in what medium.
In terms of our Onworld/Offworld distinction let us make some value judgments here: whether we like it or not, we inhabit a complex, non-linear world. In such a world, personal, immediate, and substantive communications beat impersonal, delayed, and formalistic ones. These best suit constructive, pragmatic, expert participants.
Now your “medium of communication” can take a more or less personal, and immediate form. The least personal and immediate communications are written ones (here the message is, literally, removed from the sender’s personality, and even where transmitted immediately, does not have to be answered in real time). The most personal and immediate ones are in actual, analogue person, like that ever happens these days — and failing that, a video call where you can see and hear nuance, then an audio call where you can just hear it. But any of these is vastly superior to written communication.
How many people are in your audience is just as important. The more there are, the more formal you must be, the more generalised, the less opportunity for there is for nuance and that lubricating milk of human frailty, wit. The more people there are, the less will be their common interest — cue appeals to take things off-line. Plainly, the more people there, are the greater the cultural, social and human barriers to unguarded communication rise twill there be
In any gauge of communicative effectiveness you can take, other than information dissemination, one-to-many is categorically worse than one-to-one.
Most analogue/immediate is in-person, followed by a video call, then an audio call, then in writing (and there may be a spectrum of formality in that writing too: Instant messages at one end; couriered paper at the other).
With how many people you are communicating is obvious: one is best; after that it gets worse