Generally, each site sets publishing guidelines and I won't mention those sites here.
Personally, I prefer to leave out the graphic details and write in a style that will allow the reader to "read between the lines". I think that style suits most upscale provider personas.
You may also want to set your own guidelines with your clientele.
I do agree with your philosphy that after a certain time limit, additional reviews reach diminishing returns, excluding the YMMV factors.
Good Luck to you! ;-)