At what point do personnel and expense changes render my old stories irrelevant for posting?

Granted, my memory will probably be spotty for my stories pre-covid era. Just curious since there's probably somethings I could talk about, but if it's not possible I can also give my small feedback in the reports others have done if they jog some memories. Personally just looking to share info and get ideas for my next trip.

Your question is relevant!
And generally MODs take that into account!
Common sense will guide you.

For instance, if you are in Bay Area where many Reports are posted daily, then the relevance of a 3 months Report is probably ...0.

If you write a Report about LATAM or Eastern Europe fun that is 9 months old, that could still be relevant intel for other members.

If you are in Hong Kong and you write a Reporty about a girl that is 6 mnths old but 1) is in town (actionable) and 2) nobody or very few guys have written about,
it is relevant intel for others.
If you write ~monthly a so-called "report" about the same girl (that ~everybody knows...and has her own access to this forum),
that is plain bullshit and that means that the girl is simply holding your pen, or your keyboard.
NOT GOOD.

if you write a NEW report on a girl that you wrote about before, the question is: Are there material changes that are relevant for others?
if real, then post it as Report. If less striking, post it in Mongering Talk.

If you have doubt, then make it clear in your Report so that the MODs factor in.

That how I would do.

I see!

So would Japan as well as most of Asia fall under Hong Kong standards? When I visit this year, I'll try to get a report out if I do anything interesting or new from others after my month or so there.

Also.. Say I write a report followup of a revisit. Would it be fine if I just reply into the older thread I made if anything changed/business as usual and had a good time still?

Not very experienced on THIS board, but much more on other groups in other countries.  
My take on relevance/ how far back (as a reader) would go this way:

- if it's about "how things work" in a less known area, it's usually always pertinent.  For example most people don't know much about how mongering works in Japan unless you've dived into it pretty much.  
- if it's about a specific place, I would make sure it still exists.  Example, in my new thread on my Japanese experience, I talked about older experiences in Osaka, Tobita SHinshi.  It still runs the same, so I would think it is quite pertinent.  Same goes for general activity in known walk up buildings in HK.  
- I would think the same about an agency/ club / TG group.  Just make sure they haven't changed substantially their modus operandi/ content
- if it's about a specific girl, then it will depend on how likely is it to find her in the future for other brothers.  Some girls hop from HKG to SG to Tokyo etc... I think it's pertinent, if you give these details.  But a one time visitor, 1 week and gone for ever, photoshopped pics so I would not even recognize her?  I would not care much about your report from 4 months ago...