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Learnability: This design is learnable since the layout and interaction model for similar tasks on different items is consistent. For example, the red "x" to checkout a package is the same red "x" for checking out guests and items. After typing a search term in the omni-bar, the system make is clear displays what actions are available to perform on the result by giving buttons that launch each action.
Efficiency: This design is efficient, especially when dealing with a single student's entry. Every available action (add and remove guests, packages, and items) is present from one screen, making it easy to perform multiple actions at once. For example, when a student comes down to desk to return a movie she borrowed, pick up a package, and check in her friend as a guest, the worker must only enter her name once into the omni-bar and then can perform all these actions without any further navigation.
Safety: Each entry form includes the name of the student , and the item being manipulated, and its state in the system. This helps reduce errors where packages/items might be signed in/out to the wrong person. A history of user actions (available from another accordion tab not shown in these diagrams) will allow users of the system to see their previous actions and undo them if desired.