F9-F12 are useful when you're debugging code in Visual Studio.

I sometimes use F6 to jump to my browser's address bar.

Can't imagine any uses for F7 or F8 though. And all the times I've opened a help screen with F1 have been on accident.

My main gripe with function keys on laptops is they're tiny and easy to mix up, especially since they have large brightness, volume, etc. icons on them while the function key number is a tiny label that's barely visible.

I built myself a foot pedal that presses F14. It's super useful as a global hotkey 'cause nothing else uses it. :P

F12 opens dev tools in most browsers, so I use that one all the time.

I'm pretty certain Excel supports scroll lock. It lets you scroll the sheet with the arrow keys instead of moving from cell to cell (also last time I tried you could go to the ribbon menu with the slash key, like in the good ol' Lotus 123 days). Wouldn't be surprised if it also works in other spreadsheet programs.

Blender uses F11 to view render, F12 to render, and F9 to adjust last operation. Shift+F1 through F12 switches through different editors.

And yes of course noone knows that, there's not a single person in the world who knows all Blender shortcuts. More importantly though most F keys are unassigned which means you can bind something to it without unbinding something you never heard about.

IT here. I use the F keys any time I have to change bios or bootloader settings, which is about once a month. Worst part is that no manufacturer uses the same F keys for getting into the bios/boot settings, and no bootloader either, windows and Dell change theirs over time. One Generation it's F6 to get into the bios, the next it's F8, and then a generation later it's Del. Sometimes it's F2 and F10 or F11 and F12; and almost never F3, F4, F7.

On a more positive note, Autodesk uses the F keys as hotkeys to toggle settings quickly, which is nice when I put on my drafter hat. I imagine a lot of technical software has figured this out.

I remember using F2 quite often when I was younger, but I can't remember why. I think it might have been New Game in a lot of the Windows built-in games?

That all being said... I get that these keys were originally intended for software to assign to whatever software-specific functions, as a kind of "Function keys," but we've evolved since then, and I much prefer the laptop scheme of having an extra key on the bottom row that modifies all other keys as a kind of "Function key" instead of 12 that don't do anything specific. Of the uses listed above, BIOSes/bootloaders don't have to use F keys instead of regular ones--except possibly standards requiring the other keys to always output specific characters even when the software can't use it, but if that's the case I'd love to see the devs all agree upon which keys open bios settings and which accesses the boot order menu.