A rotation can be good for determining what type of razor you enjoy using most...width, grind, etc. Variety is also a good reason, though certainly a luxury. But if you have a number of razors, brushes, etc, you may as well use them. Same with anything else, but I see soaps differently, since they offer something to others that razors and brushes don't...a variety of scents. You know that person who clearly loves their cologne/perfume but you can't stand? If you're that guy for someone, having a scent rotation exposes folks to that frustration on a less frequent basis. Plus, your nose becomes a costumed to a scent if you wear it all the time; having a rotation allows you to enjoy the scent you're wearing all the time.