How to Isolate storage hog?

My wife has a laptop with 500gb storage space. For some reason CCleaner is saying there's 366GB of system/other files. I've sorted by path and by size, but it is very very difficult to see a patter that says "Oh, Lightroom/Photoshop are storing files there and we didn't realize it" (And yes, Ive gone through all the Lightroom/Photoshop settings to make sure that's not the case, and the the best of my knowledge, it's not.

Is there any way to see which directories are the storage hogs? 366GB out of 500GB, there's gotta be a single culprit.

There are a number of third-party tools that will show that.

WinDirStat is one.

WinDirStat - Windows Directory Statistics

However, it doesn't mean files are safe to delete.

I would start by using Disk Cleanup in Windows.

Then, uninstall any applications you're not using.

Thats one thing that always scared me, not knowing what should or should not be deleted, especially with sys files. But Im pretty cautious. What Im hoping is that its some savestate cache for adobe or something. My wife uses the laptop for her two jobs. The first only utilizes the laptop for remote acces to the desktop at her work office, so no actual files are stored on the laptop for that. The second is photography, for which she uses Photoshop and Lightroom. But even then, she keeps her images on Ext HDDs. Other than that, she has no apps or programs. Well, Spotify and Office programs (Word, excel, etc), but no games, other streaming apps, or system customization apps.

"Sys" files are off limits for deletion...such as those in the Windows, Program Files, Program Files (x86), ProgramData folders.

Doing frequent disk image backups is helpful when the wrong things are deleted, or when anything goes sideways (ransomware, hard drive failure, bad update, etc.)

A disk image is an exact copy of your hard drive. Restoring an image takes your system back to exactly where it was (including shortcuts, custom settings, files, apps, Windows) when you made the image.

That said, Windows Disk Cleanup is your safest starting point.

Tools you might look into -

Macrium Reflect Free - free software for making disk images

Macrium Software | Macrium Reflect Free

A 1 TB external USB hard drive to store backups - they are now less than 50 dollars US.

Karen's Replicator - free tool to backup files and folders between disk images

Karen's Replicator the Backup Utility for Windows v3.7.6 Released May 25, 2020 | Karen's Power Tools

I have spent quite a few hrs trying to figure this out... it never fails that as soon as I post for help, I find the answer moments later. I've been continuing the search and I finally found it. It was Lightroom. I had already checked via the pref settings, but now I went through directory by directory looking at which take up the most space. Lightroom uses "catalogues", which are basically large systems for previews. Even though she wasn't storing the actual images, the program saves real-time catalogues, like its own version of memory-cache.

Tree Size Pro and its pie charts are my go to for this sort of thing.

^ TreeSizeFree is my go to for this kind of thing too.

I use Directory Report to see which directories are the storage hogs