How often do you check your lights?

Saturday the roads around here where terrible because of the cold and the snow. Lots of cars ended up in the ditch or on top of each other.

It was like driving on a sheet of ice.

But still you notice things that don't really help. So was there a car of witch the back lights didn't work at all and in the dark on the highway that means asking for problems.
After I noticed that car i started to look at more cars and noticed that there are lots of them out there of witch at least one of the lights is not working. And that made me wonder how often do i check my lights????
And do you think that they check my lights with every maintenance of the car?