A category boundary that a process crosses
The six categories classify a tea by its defining manufacturing step. That works cleanly as long as manufacture is one continuous run from fresh leaf to finished tea, and a surprising amount of tea does not work that way. A jasmine tea is a green tea made in spring, stored, and then scented in high summer when the flowers are available — two manufactures, months apart, in different seasons, and often in different provinces. A hojicha is a finished sencha or bancha put back through a machine. A shou pu-erh is a finished sun-dried maocha that is wetted and fermented. A Fu brick is a finished dark tea that is pressed and then cultivated. In each case there is a moment at which a complete, saleable product exists, and then somebody does something else to it.
Why the input being finished changes the operation
This is not merely a bookkeeping observation. A post-route acts on dry leaf, and dry leaf behaves differently from fresh leaf in ways that shape the whole operation. Dry tea is highly absorbent, which is what makes scenting possible at all — the leaf takes up floral volatiles from blossom laid against it overnight. Dry tea can be stored, which is what lets the base and the flowers be made in different seasons. Dry tea can be wetted to a chosen moisture, which is what makes a controlled microbial fermentation possible rather than a spoilage event. And dry tea can be pressed and then left, which is what allows a fungus to be cultivated inside a brick. None of those would work on fresh leaf. The post-routes exist because the input is finished, not in spite of it.
The loop, and its hidden cost
Two of these routes are loops rather than steps, and the loop has a cost that the advertising does not mention. Jasmine scenting is layer, screen out, re-dry, repeat — four to nine times for a premium tea, with entirely fresh flowers each round. Each round means another pass through a drier for the base leaf. So more rounds means more aroma and a more tired base, and the best jasmine is a balance rather than a maximum, which is exactly the opposite of how round counts are marketed. Roasting a strip oolong is the other loop: roast, rest for months, taste, roast again. Its cost is time rather than leaf, and it is why a heavily roasted oolong has a production cycle measured in seasons. In both cases the number that gets quoted — rounds, roasts — measures effort and conceals a trade-off.
Where the scheme genuinely fails, and why that is fine
Some teas have more history than the categories can express, and it is more honest to say so than to force them. A heavily roasted oolong stored for twenty years has been through edge oxidation, repeated roasting and slow change in storage; it is filed as an oolong because the oxidation decision was the defining one, and the file loses two-thirds of what happened to it. A jasmine tea is filed as a green tea, which is true and unhelpful. A hojicha is, on any strict reading, a green tea, and nobody drinking one would describe it that way. The scheme is a classification of defining steps and not a description of biography, and a reader who knows that will stop expecting it to do a job it was never built for. TeaHQ models routes alongside categories for this reason: a route can carry the whole biography, including the part that happens after the tea was already finished.