First published in TChing here and here.
Looking back through TChing posts I haven't said that much about a subject I've been focused on exploring for about two years, sheng pu'er (although reviewing versions and buying a cake / bing dates back to five years ago).
Aging concerns are only part of that tea type scope. It might make more sense to start on reviewing origin location variations and move onto other aspect differences and input causes. But that's too much for a TChing post. So is sheng aging (fermentation transitions), but I'll write about it anyway, broken by sub-theme to abbreviate things. Lately I've been more focused on how slight mustiness related to storage conditions can fade over a few months, but that's a different subject.
humidity / conditions related: the main related factor, beyond the tea itself, is how warm and humid the storage environment is. Too dry and the tea won't age; way too dry and flavor level will diminish. This article on storage condition basics goes into more on all that, with this follow-up reviewing outside input about optimums and other factors. Relatively dry stored sheng might not transition (ferment) very quickly at all, and much more humid storage can impart a range of different musty tastes. It's slightly more complicated than that but those are the basic factors.
related to the tea itself, the starting point: some sheng pu'er is great when brand new, not requiring any transition at all (although that is a matter of preference, as all the rest is). Processing input might "design" a version to be drinkable, or to emphasize storage potential. Or variation by source area tends to relate to associated character, especially initial levels of bitterness and astringency. This subject expands so much beyond that very general level I'll only address it further related to other themes (with more on it here, related to the concept of "oolong pu'er").
Laos sheng, a relatively new 2019 version (reviewed here)
slightly aged versions, versus "middle aged": depending on initial aspects some sheng might be improved, and great, after a year or two of storage and transition, or even three or four. It could make sense to prefer versions aged for longer, but preferences tend to bunch towards liking "young" (not so aged) or more-fully transitioned versions, with different people describing the awkward in-between time-frame differently. Really that wouldn't be standard; it would be a function of the starting point and storage conditions, along with preference.
fully aged sheng: people dispute what that means, although usually a relatively fixed time-frame gets mentioned along with claims. After 10 years in moderately humid storage teas can transition a lot, but 15 years is typically closer to fully aged. Even then sheng tends to keep changing, leveling off more in terms of transition beyond 20 or 30 years, per my experience (limited, for versions that old, and the oldest I've tried was still shy of aged for 40 years). Older sheng can kind of resemble shu (an idea that comes up in discussion) but per my experience it's not hard at all to tell the difference, so they can be more vaguely comparable than similar.
Tulin 2007 sheng pu'er tuocha; getting there for fermentation level
testing aging results, comparison tasting: I've done lots of this, just not relative to experienced pu'er drinkers; in a sense I'm barely getting started. In the most recent version I compared three tuochas between 4 and 7 years old (kind of in that middle range), and not long ago I compared 2006 and 2007 CNNP / China Tea sheng versions, one of which may well have been a copy of sorts. I've not been checking out the higher quality, more rare and sought after origin versions, for the obvious reason, those cost a lot. This 1980 and 1993 versions comparison covers some typical longer aging effects.
Tea Side Thai sheng, 1980 left, 1993 right
There is limited potential to assess results tied back to inputs if you aren't familiar with the starting point, but an accurate take on that requires tasting the same tea back when it was new. Some teas that are great initially tend to just fade; some that are relatively undrinkable are quite suitable for positive transitions, and others aren't. It takes an incredible amount of exposure to piece factors and trends together, but for sheng drinkers it's a labor of love.