Is `AsMut ` stable across repeated calls?

Has anyone seen a real AsMut<[T]> implementation where repeated calls to as_mut() return slices with different addresses or lengths, even when no other &mut self method is called between them? In other words, I expect this property: As long as no other &mut self method on the object is called between calls, as_mut() always returns a slice with the same address and length. I've looked at https://doc.rust-lang.org/std/convert/trait.AsMut.html and haven't found such a statement. Here is an e...