Here in New Zealand the rule is 3 seconds signalling before pulling out from the curb, turning or changing lanes.
Modern cars have indicators which flash twice a second so 6 flashes should be the minimum. And yet the number of cars I see who signal only once or twice, or better yet flash once half way through a lane change, you wouldn't believe.
As for turning the head to check the blind spot before changing lanes, ain't that what the side mirror is for? Ah no!!!
And what about staying within a lane? Oh that's right, anywhere from the curb side wheel over the fog line at the side of the road and the drivers side wheel over the centreline is just fine by most.