How often do you back up your hard drive from the PC / notebook to an external hard drive?

I always do this on New Year's Eve to make room on my notebook again.

Honestly not at all.

Important stuff I store the same always on an extra record. Is just bad when DIE times used up.

In 20 years of PC use, but just one has given up the ghost.

In that sense, I never secure my laptop's hard drives to external hard drives.

Have a clean installation of my operating system - just play up if necessary and hardly / no need to make updates.

Certain private data, movies, ditties, etc. I have stored on external hard drives.
I can re-download and install installed programs at any time.

So if new certain movies, private files, etc. Are added, they are (relatively old-fashioned) simply copied to the external hard drive (s) and done.

Every Friday evening I secure my 6 computers completely via Clonezilla image backup to external USB hard drives, the time required is a good hour.

As a software developer, I often back up my ongoing work several times an hour to ext. Hard disk, so I do not have to do my job again because of a mistake or oversight.

If e.g. An internal hard drive gives up the ghost, this is not a broken leg with me, it is a replacement HDD installed and made a restore of the backup, my current backup played back and after half an hour, everything runs smoothly again without data loss.