I uh follow patterns when I walk. Any contrast that can form patterns. Like different coloured bricks, lines in concrete, shadowed areas, steps, different types of tiles. I have a compulsion (not too strong) to step on such patterns evenly, and never to step on the boundaries of the pattern.
Patterns of bricks where the colour alternates every brick, or patterns that require a step too short or too long to be a comfortable step really annoy me. When it's like that I just try not to look down and pretend I'm not standing on the edges :/
If I am distracted by thought though I will be oblivious to this

I tend to walk like this when there are visible patterns on the ground or floor. I did it far more often as a child, and I also had the annoyance with the patterns that don't quite match my comfortable stride. I tend to dislike stepping on lines, especially, but not for any particular reason, it just feels wrong.