Did you use spades with your Furutech outlets?

[One and a half]

You mean 10AWG on a US style receptacle Furutech notwithstanding?

There's no other way really, heck I use rings actually even on 12AWG, you just get the transfer of current using bare connections.

 

Ring lugs are necessary for the ground, if the screw loosens, there's still some contact area, if a spade is used, the earth wire will most likely fall off.

[One and a half]

A crimp on a ring or spades has tons of pressure applied  causing no oxygen to be trapped between the copper and the spade. The copper becomes a solid. The right tool needs to used, ratchet types are easier on the hand a n d have tremendous force.

 

In comparison,  direct connection of copper with a screwed connection by hand is the weakest.