When Play does not go to Prep

A few weeks ago, I was running my Blades in the Dark campaign, in the Free Play stage, waiting for the players to finish gathering information to kick off their score. I figured they needed to get a few details uncovered to be ready. I had even given them a few hints in the narrative prelude, which I released the day before the session. Roll after roll, and question after question followed, and I started to realize that the players were not even close to what I had prepped for the evening, and had chosen an unexpected chain of actions. The interesting part was that through these actions, they