I think this conversation is perhaps getting sidetracked by a few confusions and misunderstandings. First, when Phaedrus says that how one comes out on the 4 dichotomies much match ones type, that is simply tautologically correct. For example, in Socionics, it doesn't make sense to say one is ILE but "S rather than N" or "F rather than T"...any more than it makes sense to say that one is ILE but "more Te than Ti." Of course one might come out on the MBTI or some other test as being more S and F even though one's really an ILE. That's simply because the tests aren't perfect.
As to conscientiousness being learned...well, again, if one thinks of the English term "conscientiousness," that certainly can be learned and is not determined by type. In the MBTI world, they like to point out that type has to do with preferences and that it's not an excuse for any sort of negative behavior. Everybody can and should learn to compensate for their own weaknesses. That doesn't negate the fact that some people must continually struggle to be organized, whereas for other people, organization comes naturally and spontaneity less naturally.