Growing out an unharvested garlic head

For some reason I tried, and I know I am not the only person to do so, as I've seen others mention doing so... was leaving a head of garlic in the ground where it had grown, and to see what happened after another year.  The response when someone else who mentioned doing this got, was that the cramped cloves would turn into much smaller heads - therefore it wasn't worth doing.

This is the garlic head sprouting way back in early July.

Unharvested garlic head sprouting 

And the same head harvested in early January, pretty much six months later.

Harvested heads from the unharvested head

These heads are tiny, and the effect of the cramped cloves is obvious.  I put a New Zealand one dollar coin in there for size perspective.  If the goal is to pick the largest cloves you grow, and to replant them to hopefully encourage larger cloves further down the line, it is common sense not to leave your garlic in the ground.  It's a waste of good seed material.