I think they should focus on ones in the Goldilocks zone of their star (it sounds like that's basically what they're doing), but should also grab random ones outside of it.

Why?

Because life might still exist outside of it. Our reference for what is habitable is based on a very, insignificantly tiny sample size: our own solar system. We know what conditions are necessary for earthly life to exist, but what if complex life can exist at extreme cold or extreme heat? Hell, what if we're the weird ones for requiring a temperate world to survive, while everyone else needs temperatures above 60c or below 0c?