I've done a few years service work, doin' house calls... I don't know how meny times so meny problems have led back thoes dang push-in type switches and recpt. The guy I used to work for has threatend to fire his guys if they every use 'em on his jobs. The bottom line is contact area. There is meny times more contact area between the screw head and the wire than there is between that tiny little tab that pinches the wire on push-in connectors. Someone else said this, and I also do it, strip the wires, include a pig-tail, twist them together, use a good wire nut, put on nice and tight. Use the screw connections on the device, connecting the pig-tailed wires... should last a long time if done properly. Like I said... think "contact area". The more, the better. It's just like oversizing wire, more is less. More area, less heat. Less heat, less fire. Or, maybe a little less flickering!
