And another one:
https://www.mybluprint.com/article/p...-line-quilting
Although she adds in one paragraph - to a certain extent it depends on one's machine. Some will only "behave well" when going only one direction - others do better when stitching lines are alternated.
Again - doing a small practice piece might be a good idea. (Although how many of us want to do that?)
My machine (a Pfaff 14741) did a decent job going in only one direction. Which also satisfied the way my logic operates.
(Well, of course, I changed direction when changing from side to side to top to bottom!)