Why this terminology exactly? A groove is an established route or routine. Not necessarily so well traveled that you break an axle in it or can’t take a detour that looks interesting, but enough that you can let yourself go on auto pilot for a bit without fear of straying too far. Then there is a rut. That is a long deep track made by repeated traffic that makes a trail nearly impossible to get off of, or it is a pattern of behavior that is dull, unproductive, and difficult to change.