It is all about the direction, and it will show up if you use a riding mower, too.
Mowing the yard was my job, weekends, starting when I was about 11 or 12. For months, I mowed the way I had seen Dad do it, ever smaller squares in the yard. The back yard was 2 acres, and it got boring. (Oh, how it got boring!) One weekend, since no one had ever told me
why we mowed this way, I went off pattern. I drove the mower "right" for the outer square, then, bored, I started a wavy pattern, weaving back and forth. And when I got done... you could see it. My dad was kind of mad about it. (Mom laughed.) I can still hear dad, though. "It looks like I hired a drunken sailor to mow the yard!
"
It took two more mowings for the pattern to fade.