I've had only one connection ever get totally loose and it involved a spade connection. I currently run banana jacks. That one time was pretty funny because I totally missed what happened and my travails involved an incredible coincidence. I almost never fiddle around with my system so I would never expect a loose connection. I do move my interconnect from my speaker amp to my headphone amp when I want to listen to headphones. On this one occasion, I forgot to switch the interconnect back to the main speaker and I turned on the mono bloc speaker amps. When I noticed this error I turned the amps off and made a quick switch and I did not wait before turning the mono blocs back on. I saw a flash in the rectifier of the right side amp, and then no music from the right speaker. I turned the amp off, and not wanting to risk any further damage, I took the amp (Audio Note Kageki) to my local dealer. At the dealership the amp worked flawlessly. I brought it home, hooked it up and it didn't work. That was when I actually tried to diagnose the problem as not involving the amp. It turned out that one of the spades to the right speaker was loose, but because it was fitted into one of those modern binding posts with a plastic hood to protect people from exposed wire, the speaker cable hung in place as though it was connected. The odds of the wire slipping off just before I saw the unrelated rectifier flash was extremely small, yet it happened and threw me off.
Bananas rule, spades drool. End of discussion.
I just checked my speaker connections. All using bananas, all nice and tight.
The number of times I’ve had spades get loose instead though.....
Point is, and it really is kind of a tongue in cheek thing, bananas beat spades for long term reliability in almost all setups. If you have to use a Cardas or Mundorf speaker terminal to ensure your spades stay tight it kind of proves my point.