At a Shinto shrine, you may notice people walking slightly to one side of the approach rather than directly down the middle. This is not because the center is forbidden. Traditionally, the exact center of the shrine path is called the seichū and is regarded as the path used by the kami, so worshippers are encouraged to leave it open.
If you know the meaning behind the custom, it feels natural to move a little to the left or right when the path is clear. An easy way to think about it is simply to leave the center open for the kami. But this is not a rigid rule like a traffic regulation saying that you must never step into the middle.
Japanese visitors sometimes walk in the center too. When a shrine is crowded, people have to follow the flow, and parents with small children cannot always control exactly where they walk. A tourist who does not know the custom is also unlikely to be regarded as terribly rude simply for walking down the middle.
Even so, if the approach is wide and almost empty and someone continues walking directly along the center, it can feel slightly odd. It is usually not seen as a serious breach of etiquette. The feeling is closer to, “That is the part people normally leave open.”
That difference in tone is important when understanding shrine etiquette. Avoiding the center has a religious meaning, but the custom is not meant to make people anxious about getting every detail right. If you know the custom, walk a little to the side. If circumstances lead you through the center, there is no need to worry.
What matters most is not following every point of etiquette perfectly, but treating the shrine with respect. Leaving the center of the path open is simply one small way of showing respect to the kami.
