I second that, @LuckyCyborg.

I had to resize up a 25G / partition. I set it at 40G, and it needed housekeeping there. I did have a few AppImages, a plethora of /tmp space wasted, but was not doing wild stuff. But you can get a load of data-heavy software filling up space exceedingly quickly.

In the past I used 30 Go for '/' and have also 10 Go for '/var' and '/tmp' in tmpfs. '/home' is a lot bigger and elsewhere.

Nowadays I keep the same sizes except for '/' which I extend to 50Go. 30 Go is a little too short for Slackware with useful add like openoffice, multimedia tools and usefull SBo, Ponce, Conraid or Alien or other packages.