If it's a strait up fight, I don't usually bother since hunger stress doesn't activate until the end of the scene. Especially if the guy in question isn't squeamish about killing. It's completely relative to the situation though. Like, if they're purposely running an endurance game against it to wear it down. Then, yes, that would be a good time to keep track. Alternately if you're in more of a social setting and the only easy prey happens to be a non-combat oriented friend of the PC's. Or someone they'll miss. That's a decent, "well you did drive him to this" scenario.
Overall, unless it's specific to the situation it's mostly micromanaging.