Do you store your data compressed?

Depends on what it is. If it's accessed normally, it's uncompressed. If I'm archiving it, I use LZMA2 compression.

I do use filesystem compression though

I hope you aren't using LZMA2 on already compressed media files.

You might save a few kilobytes off of a 1GB .mp4.

I don't compress media files, those are the normally accessed ones.

Only for data that I won't use for a very long time.

This. Except with btrfs, and lzo compression instead of what I'm assuming you're using, lz4. And, yeah, most digital media is already compressed in some way or another, such as comic books with cbz cba, but it's nice to sqeeze out as much space as humanly possible. The overhead isn't really that bad, and, I figured I might as well use that excess ram I never use for something useful.

Bit rot is also the reason I use flac. I couldn't give two shits about the quality of audio +198kbps, but the very thought degradation makes me foaming-at-the-mouth neurotic

Sometimes when I'll very very scarcely need the data, and even then I'll use squashfs as I basically never compress a single huge file. I also use xz in a pipe over ssh sometimes if the bandwidth between the two endpoints is smaller than the throughput of xz on the sending side.

Yes. I've messed with tons of compression formats too.
>LZO- fast as fuck for both compression and decompression, but has lowest compression ratio. I use it if I need to transfer a big (usually tar) file to another machine when the transfer speed isn't very fast; I can often cut transfer time in half if the content wasn't already compressed.
>gzip- OK speed, OK compression. Don't use this much, mainly for html files as browsers can still open gzipped ones.
>bzip2- middle ground of speed and ratio, often beats xz when compressing plaintext
>xz- good compression, can take longer

>lrzip- makes other compressors more efficient but the resulting file must be decompressed by lrzip. Has built in support for LZO, gzip, bzip2, lzma, and zpaq.
>zpaq- Best compression, takes much much longer than xz. Comes with lrzip, may be possible to use it without. Decompression takes as long as compression.

I don't use 7z, zip, or rar. 7z is a rebranded xz with a GUI and a shitty CLI version. Which program I use depends on how often I need the files, how big the file is.

yes, mostly installers and old meme folders

>compress with 7-zip
>use the balls to the walls preset that utilizes 100% of my 8-core ryzen processor
>takes like half an hour
>no file size change on my folder with raw pictures

so this is the power of open source