I don't really bother.
Once in awhile when I'm bored I'll go on MAL and add some stuff if I remember but that happens once every few months, maybe like 3 times a year.
I guess it's not like I delete anything though, so my progress is scattered throughout my computer, since I don't really organize anything either.
Currently ongoing stuff that I am watching/reading: remove all episodes/chapters before the last one I finished.
Finished stuff: Watch it in one go or figure out where I left off from quick sampling.
Stuff that I have completed: excel sheet. Every once in a while I turn the list into a really autistic desktop background.
I keep track of everything (Anime, Manga, LNs, VNs, etc) in an Excel workbook. Although, I've been forgetting to update it lately, which ends up bugging me because I'm pretty sure I finished some series and never added them to the list. Would be nice if I could work up the effort to automate the process a bit.
>tfw suddenly the internet fails for no reason and you're stuck with what you've downloaded for the next month
>tfw suddenly your only regret is that you didn't replace old downloads with better encodes
>Literal autists comparing how many Terabytes of chinese cartoons they havent watched
Finished stuff: Download everything and make a folder for it. If it's something I don't care about I delete every episode/chapter once I'm done watching/reading it. Otherwise I make a subfolder named "read" or "watched" and move things there as I go through them. If it's a tankobon or light novel I really want to keep, the "read" subfolder becomes a folder for each chapter since they're usually not sorted. I create those as I read. When I finish I have each volume neatly sorted.
Ongoing stuff: Make a folder and download as I read/watch.
Why OP, MAL takes two seconds to update.
Swallow your pride and stop this nonsense.
I use pic related
best invention since the wheel
I've got a folder for stuff I haven't started/finished, and a folder for stuff I've finished.
As I finish an episode I'll change the file name (for example, from '[LIME]_Ichigo_Mashimaro_04_[DVD][800x450]' to 'Ichigo Mashimaro 04').
Once I'm done the entire series/season/whatever, I'll move the series folder into my 'completed' folder and also change the folder name for that if it needs it. I also change the folder image from the default to the logo of the show (for a series, not for each season - which goes inside the series folder)
I use MAL, not for the community. Do people really get annoyed with that?