If you are "educated", then you are "supposed to" pronounce the middle constantans, as skipping them is considered "lazy". I'm not making a value judgement, but reporting that this is what parents often tell their kids in private. All things being equal, parents want their children to sound wealthy and well educated. Similar for certain rural or "redneck" talk in the US. Example: "Murica" instead of "America". My mother used to lecture me against certain verbal shortcuts so that I didn't "sound ignorant". Her words, not mine.
I agree. The downside of the loosening of the old standard is heard in the number of actors who mumble through their lines. I wouldn't want to go back to a time when RADA enforced a kind of RP but I would like them to focus just as hard on diction.
[0]: https://books.google.co.uk/books?id=YMS3AwAAQBAJ&pg=PT26&lpg...
You might feel a lot more comfortable talking about this subject and find useful alternatives to your scare-quoted words if you skim https://en.wikipedia.org/wiki/Sociolinguistics
Also due to https://en.wikipedia.org/wiki/Hypercorrection ,I think https://en.wikipedia.org/wiki/Rhoticity_in_English is a fascinating and accessible example. A terrible summary: dropping the R is lazy (dropping anything is "lazy"), but at the same time sounds British and therefore fancy to some American ears. But other people, to avoid laziness, add Rs. But then their speech can sound low-status in some cases too.
I correct my childrens' pronunciations. I've honestly never thought of it as a class thing. In part it's "inherited", so it could have consciously been a class thing for one of my ancestors. But really to me it just seems necessary for preliterate speakers to understand the proper way to say a word based on its spelling, which they don't know. I find myself correcting USA-ian word use ("garbage") and pronunciation far more with my youngest than I had to at that age with my oldest ... we probably let him watch too much TV (several shows, like Paw Patrol have shifted to USA versions from British English versions).
It's hard to discern every phoneme from a new word, and hard to say some of them.
I do shift my accent, and vocabulary, to mark myself as a local I guess (when I'm back in that area of the country). If I get to use certain words in their localised (to about a 20mi long area) meaning it makes me happy for some reason. But I've never consciously worked on my accent to sound more/less posh; but have modified it to be more understood.
My wife is what I call a 'sympathetic speaker', she very quickly adopts the accent of those she's speaking with. An interesting phenomenon.
Politicians are often known to do the same. It's usually painted as "pandering", but I'm not making a value judgement here. There's arguments both for and against.