What did I miss about QT?

[Anatopism]

Obviously everybody will have different opinions on how long is adequate for QT, the longer you go the safer you are. IBD can lay dormant in a boa for years, but is typically fatal for python species, and my understanding is that if a python has been exposed, you will see symptoms within 3 months. Just because a disease or illness may lay dormant for a snake's entire life does not mean it is useless to QT, as you are giving yourself and your other snakes an opportunity to notice symptoms and avoid disaster.

Keep in mind too, that external parasites are not the only thing to look out for, and you will not always notice a single or even a small handful of mites until you do allow for the full and typical life stages. Some people treat for mites even if they don't see them, as a preventative.

There are also things like pinworms where if you do not allow enough time to observe several feedings, poops, and overall health of an animal, you might miss entirely. A new snake may be infected with pinworms, and you may QT for two weeks, but unless you do a fecal sample, you may not notice a gradual weight loss in the animal until they have been introduced to the rest of your collection.

You might notice an RI right away, but the above paragraph also applies. A lot of snakes develop symptoms very slowly, and its smart to allow for adequate observation time, so your other animals are safe.

Again... same paragraph applies... but cryptosporidium is notoriously difficult to notice/diagnose, but it can be disastrous to a reptile and your collection. Allowing for enough time to observe the overall well-being of a snake is a safeguard against crisis.

A QT period is never a guarantee, but is a necessity.