With Linux filesystem hierarchies you're going to run into a lot of history, conventions, quasi-standards and simply deprecated implementations.

It's a problem of "there's no bad way to do it so all options are equally fine". From this arose some "guidelines" about /bin and /usr/bin, /var, etc. but few strict rules.

For a long time there was no /media. In the '90s/2000's you would mount your CD-ROM and floppies in /mnt (e.g. /mnt/cdrom, /mnt/floppy). That was awkward as we started wanting auto-mounted things and wanted to do it from user-space. So /media/username was created to allow you to mount things with your ownership.

If it's something you want permanently mounted but not part of a pool you can put it under any location you like really. I like locations under /var as historically /var is used for things that "vary". You could just mount it in your $HOME if it's something you're going to use as a user rather than with a service.

I have a "/exports" dir for NFS mounts (e.g. /export/media, /export/storage, etc.). Just keeps it tidy and in one location.

The important thing is to use a standard that works for you and makes sense. There's not a lot of bad places to mount things. If "/mnt" makes sense for you then go for it.

Anything I add to fstab gets mounted in /mnt and removable drives get auto mounted to /media. Linux doesn't care where you mount your drives, they can be mounted anywhere you want.

Mount your internal disks to /D:, /E:, /F:, etc.

It ultimately doesn't actually matter because in many cases these things are convention and there is no real system-based effect. So while it would be especially weird if your distro installed packages into those directories, it ultimately doesn't matter. Someone already linked the filesystem hirearchy. See how tiny the /media and /mnt sections are?

I put my fixed disks into subdirectories under /mnt and I mount my NAS shares (I keep it offline most of the time) in subdirectories in /media.

Mounting locations are a convention, not a standard, mount whatever you like wherever you like. In your case, I'd mount it under /mnt/ntfs, /mnt/windows if it a windows main partition you want visible, or by drive letter if it's a secondary drive on a dual-boot system.

Or however you want. I would keep it under /mnt, but you don't have to.

Do maybe sure you have user permissions set up properly if this is a multiuser machine though

Edit: also I would interpret

If /mnt is for temporary

'temporary' as in 'may become unmounted without seriously fucking the system'

/ and /home aren't temporary. Everywhere else is

Idk, I mount my disks in /mnt/whatever, though I don't think it matters where you mount them.

/C:

Use any you want. I've been mounting my internal secondary hard drive on /mnt for well over a year now and haven't had any problems. Previously, I mounted it on ~/Storage and it also worked fine (though only because I'm the only user in my computer; dual-user systems would result in the other user being unable to access the hard drive).

The best mounting position is /booty.

Basically if I add it to my fstab it goes to /mnt. I let the system handle /media for usb etc

I create /data and mount my 2nd drive there using fstab.

I then mount /data/downloads under my user downloads folder so everything goes to my 2nd drive. That way I dont have to redownload anything if I redo my main drive.

The Linux FHS does not address this, so it's up to you where to mount it. There is no correct choice, but if you want to follow standards just mount it inside /mnt which is the nearest use-case (/media could be automatically used by your DE, so avoid it). Otherwise you can just create a custom folder in root like someone else suggested.

Take a look at FHS spec.

Edit:
On arch forum someone suggests /mnt/data

There's also /run/media/[username]/. Don't know if it's an OpenSUSE thing or Plasma but everything I mount through KDE's file manager Dolphin ends up there. Including stuff I set up to mount automatically.

Permanent drives should be put wherever you want them to, for example I have mine mounted in /ld1 for Large Disk 1. /media is supposed to be used by systems to mount things you plug, but some systems move that to /var/run/media or other places. /mnt is there so you don't have to create a folder in case you want to mount something really quick.

Not a pro by any means, but I mount my internal drives at /mnt. Its also where I mount my NAS

AFAIK mount point doesn't matter

Actually since their permanent non-removable drives, I would say wherever you want to place them, if they're meant primarily for storing user-based data you can do like what I used to do which was store them in within the home directory just as specific names. Like my old setup before I went proxmox was /backups was my backup drive, /home was my home drive that stored most of my users /home/steam held all my game server drive and /home/storage held my long term cold storage drive.

In the past I've tended towards /srv/* as most mounts end up being application specific storage.

Though now it is all mounted as container volume storage.

Unless dictated by the particular data in the disks, /mnt is generally used for system managed volumes and /media is used for user managed volumes.

If you do something else, stick with it so you don’t get confused.

I use multiple subdirectories under /mnt for my fstab/systemd-mount managed disks. That includes local and network locations.

As far as I'm concerned, everything goes under /mnt , and has for the past 18+ years.

If I remember correctly mnt is for static media that you expect to always be present and media is for removable media which may come and go.

If they’re internal drives then you choose.

I like to mount drives at root, their parent directory being the logical purpose of the drive.

Got a drive you added that’s gonna be for games?

/games

Is it for movies?

/movies

Or maybe it’s just general data storage?

/data

No need to make it more complicated than it has to be.

This is standard across the industry, unless you are mounting disks that would conform to another strategy (say it’s a drive of repos, it might mounted under /usr/local/src/ as that’s where one would expect user provided source code).

I myself have separate /Disks folder where I mount all my internal disks on boot. Not sure how "standard" such setup is, but it helped me keep my NTFS and Linux disks tidy and out of my way. For what I know you can mount your drives anywhere you like