The roving Insert point is harder to implement, due to the reversed case:
[ ][ ][I][ ][ ][H][ ][ ]
^^^^^^^^
`these items move right
[ ][ ][H][ ][I][ ][ ][ ]
^^^^ ^^^^^^^ ^- this item moves to the top (left most slot)
| `--- these items move right
` these items move right
If we think about doing it in hardware, like for each set of a set-associative L1 or L2 cache, it's a hindrance.
