I have always torqued my rings until I **** near can't get them any tighter with an L-shaped allen or torx wrench. I had my Nikon 4-12x40 loosen up on my 338WM once, It beat the scope tube in front of the power ring into the scope ring so many times and so hard it had metal pealing over a little.
It only left marks under the ring with only a couple telltale scratches in front of it. The crosshairs started to rotate, that gave it away. Since then they get torqued down crushed or not. The only one that ever crushed was the Nikon and it is just barely noticable if you slide your finger down it.
The Leopold 3.5-10x40 on my Ruger 416WBY got the same heavy hand. It did not crush with the original Ruger rings or he new Burris Posi-Line rings I might add.
The Burris rings only have two screws in each ring and I wondered about their ability, but they've held up just fine for about 100 rounds so far with no slippage, and that monster has some recoil too.
The 5.5-22x56 NF was cinched up good like the others too. No scratches, no crushed tube and all was well when I removed it for a visit to Nightforce.
I don't like them comming loose, screw the torque specs in my book. I'm sure mine are over torqued, but how much I'm not sure. The screws stop turning though.