[u-u] Bash best practices?

[arocker at Vex.Net]

Is there any official consensus on where bash function libraries should be
kept and how they should be invoked?

There's a spectrum of flexibility vs certainty between "in a system
directory, invoked at every invocation of bash" and "in a private bin,
explicitly sourced in every script".

I could lay out the arguments for most of the possible positions, but my
little voices have other things to discuss.

All evidence-based opinions welcomed.