there's lots of good info in this thread
for my 2cents worth, i do a similar thing to havadrpepper - i download to a new folder each month. (So within the Downloads folder i make a new folder, this month's is Feb 2022 - anything i download this month goes into there and that way, it kind of forces me to sort things and back them up at the end of each month. After MOC i have a backlog and still haven't sorted through Jan 2022's folder yet but that kept getting bumped off my to-do lists).
Anyhow, i then do a similar thing to bestcee, going designer by designer if it's been a big event weekend like DSD, i agree it is slower but it feels like crossing things off a list, and i do the same when doing back-ups. Going one by one is a bit less confusing for me and it's easier to do in small chunks of time between errands and just so i'm not staring at the computer screen for long periods. i can do say 3 or 4 designer folders then get up and give my eyes a break. If you have years worth to do, make sure you are having lots of breaks!
Like BevG also, i'm not a lover of sub-folders so i add most designers stuff into a single folder too like Kat, unless it's an alpha pack (and i know i really won't want to scroll through all the letters & numbers in several colours just to find everything else that was in the elements or paper pack) - i delete the zips after everything by that particular designer is unzipped and checked.
the only real things i don't keep after unzipping are the PSD's and separate PNG files that come in some template zips (i know there are some people that prefer PSD's etc, but me, i like TIFF files, i've been using TIFF files for probably close to a decade now with Photoshop and while i love that designers are so nice that they put in all the different possible template formats, if i'm unzipping and want to save space, i only keep that version of the template; but some designers let you just download the format you want, so in that case, i grab the TIFF file and it's one less step in the unzipping process for me).
Filenames, because i store things by designer, like others have said, i just leave the filenames as they come - if i know i'm looking for an Artsy Bits and Pieces pack or piece of it, i know i can find it in my NBK folder under ABP. Her names are always consistent and her collections have so many parts that I keep her folders separate because in that case, subfolders are actually easier for me - so this is where offering organisation and file sorting help can be a bit difficult and differs for people - it might be hard to have just one rule for storing things and your organisation depending on what you have and how you scrap.
You are welcome 
