The only photos I backup are my certificates.
Rest are non-essential and don't deserve more than one copy.

I recently lost quite a few videos, moving a partition to the left and it didn't matter enough for me to consider backing them up next time.

The source codes I make however, apart from having them on gitlab, I am also considering keeping a separate drive to store them.
With patches to other projects, stored as diffs instead of storing the whole project.