I have a 150GB temp directory on my laptop, and I don't consider myself a power user (no video/audio editing, no modern games, etc.). 256GB is really tiny, even for my mother who just keeps local copies of photos and documents etc.
("temp" like "stuff I occasionally need", not literally /var/tmp)
I do have a 4 TB NAS at home, but that's backups and childhood photos, no daily-driving stuff. I don't consider myself a casual user.