PKG install size question

I installed game updates totalling about 21GBs. I read that updates are stored in dev_hdd0 but that folder is just 1.6GB. I read that I can delete the pkg updates if I backup the hdd folder but I'd like to confirm they're installed first. Is hdd0 compressed in some way?

If updates are replacing the same files over and over, it would make sense that the installers combined are very big but not the resulting files. hdd0 is not compressed.
Have you already ran the game? It didn't install any extra game data to hdd0?

If updates are replacing the same files over and over, it would make sense that the installers combined are very big but not the resulting files. hdd0 is not compressed.
Have you already ran the game? It didn't install any extra game data to hdd0?

It's more than a few games, actually. I've ran a few of them and yes, it did for two. But the hdd0 folder didn't seem to increase in size, although I didn't notice at the kb level, only GB, so maybe it did install there.