[velma]

I think it depends on the ham. Some of my hamsters have had the biggest sulk if you change even one tiny thing around (not including chews etc) so like cypher's ham for them it would be never and I've had others who got bored quickly and liked the change. I think for a lot of hams then if you do want to change something it's best to make gradual little changes so you don't stress them out.