not so long. especially Augustinavichiute
that they did something practically useful is a miracle. Jung could not even to think that types can be used in duality to heal psyche and to make good pairs. more to say the common Jungian conception was that duality is mostly bad and prevents personal growth and abbility to be healthy. they can be partly right if to don't use the idea of deep love in pairs, - that overcomes such issues through introjection of the dual
That's nice and all, but they didn't actually turn their observations into some kind of quantifiable data. For example in modern psychology, you are required to put the results of your experiments into statistics, because that's how you can eliminate as much biases and errors as possible (and we know this because statistics are "mathematically proven" to eliminate human errors and biases). I don't think mere observations are good enough, because they are prone to error if they "just stay inside of our own heads".
What Jung and Augusta were doing were essentially "psychoanalysis". It's about coming up with explanations for people's motives and behaviors, even though it can't exactly be proven. The problem with "psychoanalysis" is that you can literally come up with ANY explanations for people's motives, all because "it can not be proven". We can almost never prove what people are "really" thinking, because we have no direct access to people's thoughts and brains. So you can essentially come up with any kind of explanations, like "The reason why you behave that way is because of your relation with your mother" "The reason why you're so pessimistic is because of your death-instinct, it's the libido-theory" "The reason why you think so is because of your Hidden Agenda"... well sure, they could be right and plausible but they also can't be proven.
So anyway, this is nothing new... the "hard" scientists have been criticizing and making fun of psychologists for this very reason since the days of Freud and Jung. And you know, I used to side with the "psychologists", saying that "Well, objectivity isn't everything...! Subjectivity must also be considered...", but now I see the point of the scientists. Sure our subjectivity should be considered, but so should objectivity. We can't just make things up and claim that we are right without any proof and evidence, especially since we are so prone to our own human errors and biases.
So I think the reason why people tend to believe in these "typologies" is mainly due to ignorance of the history and fields of psychology. They don't know that we've already gone through this phase and that they have mainly fallen out of favor for more objectivity. And that's probably why actual psychologists and scientists don't tend to take these "typologies" seriously.
It seems like what Jung was warning against were one-sided development. He didn't exactly say that there were these exact "types", it's just that too much one-sided development in certain "functions" was detrimental to your growth and it's what makes you more "neurotic". So too much Te turns into someone who only sticks to facts but are otherwise boring, too much Fe turns you into someone who only follows social norms and apparently unthinking, too much Ni turns you into an eccentric crank, and so on... He claimed that we had "strong, conscious, and in-control functions", and "weak, unconscious, primitive and immature functions" (which are probably proven wrong by brain science, but ok). And he also claimed that the use of each functions suppressed all the other functions, and not just their opposing functions. So using T suppressed all F, S and N.