In my mind, as soon as you approach anything remotely resembling "fancy," you should move on to a different language or framework that isn't a bash or shell script at all.

I start questioning whether I should be writing bash as soon as I hit about ten lines. I won't even consider writing functions or loops.

If I'm manipulating the system, I'm probably using configuration management, and for most other tasks, I'm using a full-blown programming language with a nice set of standard libraries.

E.g., Python and Ansible.