I learned to type on an electric typewriter, not a computer keyboard. Consequently I developed a habit of double spacing after each period, as that was normal practice on that medium. A colleague pointed my double spacing out a year or two ago when peer reviewing some code for which I had created some comments. It got me thinking, but I didn’t consider stopping use of double spaces for some time after that. Lately though, I have started using single spacing. It’s strange to break a long-held habit, but by the same token refreshing. I am looking for more intrinsic habits to break as a result.