Spades are a bolted joint. Bolted joints are used a lot in a lot of places. The one time they have a vulnerability is the configuration like a spade connector. Generally they have a washer under them that doesn't stick out. But a spade sticks out. So long as the spade/wire isn't touched or pulled, all is well, but if the entnding lever is bumped or pulled, it will loosen the connection.
So I'm sure some people have great luck with them, as their connections live a quiet life. Others, not so much.
Just wanting to point out why we have different reports of experinces.
Jerry