I feel like there's been many threads on this before, perhaps even one of them was started by me, so this may be a tired topic.
At time I have a paranoid fear that people place an undue prominence on subtypes - perhaps even focussing more on subtypes than on the base types themselves. I suppose there's not so much "wrong" with that if in the minds of these people, the types are subconsciously ingrained into their minds and so it does not pay to focus too much attention on the types.
However, it seems that on a frequent basis, key aspects of behaviour are explained away not as being relevant to an individual's type, but to a particular subtype - often seeming as though they are fixed on a type contrary to significant evidence.
I regularly find that when I attempt to type someone, perhaps as many as three or four types come readily to mind - and then it is clear that it is not time to ascertain a guess on that person's type - it would be better to reflect, and perhaps make more observations and listen to the reasonings of others. It would not do in such a situation to try and explain away things via the subtype method.
It would be best to keep in mind the core elements of each of the 16 types - and ultimately decide on that person's type. It's rare too that I see a type-subtype combo being used in the context of intertype relations - and if I do, I recall it being do in a slightly confused manner - i.e. the people seem inhuman and\or their actions are broken down to such a level I wonder what would be wrong with simply talking about types and functions.
Another irk of mine is someone being typed for example "LSE-Te 4w3 Sp\Sx to the Max" or some such, but actually, I don't think I've seen that for some time.