I always delete the coffee machine. The animation takes too long, which is the reason why the little boost never results in anything else than that the sim drinking coffee ends at exactly the same place where they started. That's why they start again. If the sim gets really tired, the decision paralysis that usually comes with that state does them in, and they are stuck in an endless cycle.
The Sims3 coffee machine's only purpose is to show you how addiction works. Maybe. Or in other words: It's disruptive. Delete.