I recently had a personal experience with a bad connection at a junction box.
Four neutral in one wire nut(correct size)
One of the neutrals did not make up tight in the wire nut and it started arcing with eventual loss of neutral on that circuit string.
I was lucky to find it.
This can go on for years before presenting a problem.
I once had to troubleshoot a problem to a circuit supplying some surgical suites.
Loose neutral lug in a large panel. Must never have been torqued to spec.
It was that way for nearly a decade.