If sales prices of land deviate from zero, and the land value tax is meant to take the full amount of land rent, that's when the land tax is too high or too low. This can also be estimated by the replacement values of structures versus transaction prices. The devil is in the details of quickly changing markets, however. But with a full LVT markets would change far less quickly because there would be far less speculation, and less of a bubble on land prices, because more land would be opened up to the desires of society as a whole instead of the desires of the few rentiers holding it.

The other way of looking at this is imputed rent, the amount of money that somebody would be willing to pay to rent out their own home. Well, in theory it would be that amount. In high-demand areas, homeowners' actual imputed rent is higher than they would be willing to pay, because the act of buying property and paying low taxes let's then live in their place for far less than somebody else would pay for the same privilege. Which is how opportunity get hoarded, and how rentiers take over local governance structures.