Good point! One thing we always considered in the AI lab is - it is often better to quickly get an adequate answer than take lots of time to get a perfect answer. Take some time to make sure you aren't stuck in a local energy well by jumping around a lot, but eventually produce an answer without knowing if hoping over that next mountain will land you in an even lower valley, where the lowest landscape point is the best answer.
We were doing expert systems for the military, and a good quick answer is better than a slow perfect answer that you are too dead to use.
Yes, as is often the case these questions are kind of perfect world scenarios, and are just there for the sake of sound theory. But yes, an aproximate answer is better than no answer at all.
Cryptogee