Yes, yes. I meant that people do not intuitively understand or follow these rules, as asserted by the post I was replying to. People routinely fail to follow them, and lots of people I have direct contact with don't even understand why being ambiguous when giving directions for a job is a bad thing.
I have a perfect example of this: one person I know, when he says "next Monday" only truly means the next immediate Monday when it's more than 3-4 days away and never when next Monday is tomorrow. In all other cases he'll say "this Monday" when he means the next one, and "the 'other' Monday" when he means the one after the next one. It seems to be a very imprecise function of the distance to the actual next Monday.
Now, some considerations: some people actually talk like this in informal contexts, though not everyone and there's no way of always knowing the context. Also, I'm translating from Spanish; presumably the English vernacular has similar imprecise conventions.
What drives me crazy is that this imprecise language is used when arranging a date or scheduling some job. "Next Monday I have a doctor's appointment", or "This task will be finished next Monday". This person is always puzzled when I ask him to clarify what he means by "next Monday" -- is it the actual next Monday or the other Monday?
Of course many times you can guess by context, especially if you're familiar with this convention, but it's not always possible and it catches people unfamiliar with the convention off-guard.
And this is just an example. It happens all the time, with lots of people, with lots of ambiguities that have real impact. People absolutely do NOT follow these maxims of conversation.
Another example: I could have explained all of this way more concisely. I chose to rant instead ;)