The parade looks like an epitaphio procession! Why don’t people march in straight lines?
A few groups have successfully marched in formation (e.g. Kyklos Hellenic Society). They have succeeded because they planned ahead and practiced. If you want your group to look neat, you should practice. We’ve tried various methods to get people to line up neatly, but we’ve learned that nothing will work if you don’t practice ahead of time.
