A medical system includes a flexible elongate instrument and a control system. The flexible elongate instrument includes a plurality of wires useable to control articulation of the flexible elongate instrument. The control system is configured to monitor movement of the flexible elongate instrument, determine an extent of motion of the flexible elongate instrument based on the monitoring, and determine a mode of operation for the flexible elongate instrument from a plurality of modes of operation based on the monitoring. The plurality of modes of operation includes a retraction mode, an insertion mode, and a parking mode. The control system is further configured to, in response to a change in the mode of operation, alter a rigidity of the flexible elongate instrument with a rate of rigidity change that is based on the extent of motion using one or more of the plurality of wires.