Does a normal desktop user need to install "devel" and "kernel-generic-debug"

[Annalesa]

I think install the FreeBSD-set-optional is enough

 

[Maturin]

Of course. You don't need devel unless you want to develop.
Anyway you can install it afterwards, when you changed your mind, or your situation changed.
On the other hand, if you don't need to count every each MByte, it doesn't hurt, if it's onboard.

 

[Hello]

No

 

[atax1a]

you only need the debug sets if you're doing kernel debugging, but devel tends to be generally useful imo.