I was kind of thinking expected value. In principle, if you always go by expected value, in the long run you will end up maximizing your value. But this may not be the best move to make if you're low on resources, because with bad luck you'll run out of them and die even though you made the moves with the highest expected value.

However, your objection does make sense and Eby's reformulation of my theory is probably the superior one, now that I think about it.