One insider threat actor might book a previously unbugged desk, bug it with multi-antenna keystroke logger (making and breaking resistive connections across parasitic capacitance nodes, changes the direction dependent EM scattering function). One can correlate acoustic key press detection with changes in scattering, unsupervised.

Fixed desks are way more secure than promiscuous desk multiplexing.

An insider threat actor can just do that without booking the desk. They just go in on a quiet day and sit down, nobody checks whether a desk is booked unless they themselves need to sit there.