In the beginner mode, the app does not care about the marker's location. In the singularity mode, the order in which the reminders are selected depends on the location of the black marker. The black arrow aligns with the black marker indicating when you went to sleep last night. The silver arrow shows when you stopped the app last time.

In future releases, once I put smart alarms in, the location of the black marker would help indicate when the smart alarm would be played. I'm still trying to determine the best way to do this without adding extra complexity. This is why the dial does not align itself automatically yet.

And yes, the idea is that the less you have to move the black marker the better your sleep schedule is. It takes your body time to adjust and synchronize it's multiple internal biological clocks, and the process cannot be accomplished overnight. Automatically aligning the dial with whenever you go to sleep would make it seem like you have control over this aspect of your body, while in reality you do not.