I noticed today i go one hand when the roads are narrow & speeds are crawling ,my hand is usually on the hand break,as i am under the habit of keeping the car in neutral & applying the hand break when still in traffic,under crawling city driving condition its fine ,but when your speeds are up two hands are the way to go!
I remember an incident some months ago when i was travelling on the highway at 4 early morning,i was doing 120 plus all the time as i knew the road well & roads were empty,for more than an hour i had not relaxed my concentration,then for a few seconds i took one hand off the wheel & to my horror there was someones black coloured pet dog in the right hand lane(sniffing something on the road i assume
),with one hand i had to shift lanes towards the extreme left,it was like pulling a u-turn at 120 & straightening the wheel immediately,it made me realize how important it is to keep both hands on the wheel,you cannot give instant steering respond with one hand,well atleast not as well when you have both hands on.