I don't know much about academic consequentialism, but I'd be surprised if someone hadn't come up with the idea of the utilon x second, ie adding a time dimension and trying to maximize utilon x seconds. If giving someone a new car only makes them happier for the first few weeks, then that only provides so many utilon x seconds. If getting married makes you happier for the rest of your life, well, that provides more utilon x seconds. If you want to know whether you should invest your effort in getting people more cars or getting them into relationships, you'll want to take that into account.

This is one reason I say my notional utility function is defined over 4D histories of the entire universe, not any smaller structures like people.