Optimum block time

[nuggetbram]

As a hypothetical situation, what would be the optimum block time for a coin to be worth $1 USD?

A coin that isn't hugely popular or anything, just "around" with a block reward of 1 for simplicity, what do you think would be the best block time to give this coin a $1 value? Or does it really not have anything to do with the mathematical rarity and more how the coin is adopted and used?