No, I am talking about the rolling cache. I am not talking about pre-loading data.
With my 64 GB of memory, my Rolling Cache is set to the default 8 GB
with no problems.
And I fly the same Flight Plan quite often.
yes Ron… the rolling cache just prevent to load some online data again… therefore is also 8GIG (the default) sufficent, depends bit on flight profile 
I also assume that a cache size, which itself can cached from windows within the memory, is a good choice.
I still think that depends a lot on your individual circumstances.
If internet data volume and internet bandwidth is an issue (e.g., you live in a rural area and rely on satellite broadband) and if you fly several times in the same area before going somewhere else a large cache size could help. In that case a large rolling cache saves the inconvenience of reconfiguring the manual cache when moving on.
Same internet situation and usually flying in one specific favorite area is where manual cache really makes sense since there is less need for manual reconfiguration.
And if internet data is not an issue a large cache is less necessary no matter where and how you fly, and I think that is where sizing cache based on RAM starts making sense.
No may not be correct … my file C:\Users\billi\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe is up to about 291 GB (this is with rolling cache of 100 GB) now, the total 1 TB NVME is 475 GB now, only MSFS, Win 11, email, and a few other utilities, initially it was 190 GB, at one point it seemed to be up to 490 GB and I found out that that was my oversized rolling cache and something else, and I brought the size back down, I do have a few aftermarket sceneries and freeware planes and helicopters, I have a second 1 TB SSD but haven’t used it at all …
150 - 200 GB is about right … check size of rolling cache … in the past I had this inadvertently at 100 MB and manual cache at 100 MB and total size was 390 MB …