Are EMT connectors (couplers, etc.) prone to disconnecting?
No. Code would not allow it if it was a significant risk.
Do be sure to properly tighten all the screws and threaded connections, but they don't just randomly break or &quot;go bad.&quot;
Or: Consider that when you use grounding wires, &quot;one bad screw will break the path to ground&quot;, too.