The fatal accident inquiry at Stornoway Sheriff Court heard speech therapist Lorna Macdonald wrote "epic car journey" on an office whiteboard on the morning of her death to describe a 120-mile return trip to see a patient.
The 26-year-old, of Cross Street, Stornoway, died after her vehicle plunged into a loch between Leverburgh and Tarbert, Harris, during a storm in November 2011.
After her death, her employer, Western Isles NHS, introduced written guidance over bad weather working.
Ms Macdonald's manager Christine Lapsley stressed she expected her staff to be responsible for their own safety and to heed the weather conditions. She said she closed her office in Benbecula early due to the severe conditions that day and phoned the Stornoway office at 2.30pm to suggest they may do the same.
She said: "There was nobody in the office in Stornoway so I left a message to say, "go home - be careful."
The absence of staff in the office "did indicate to me that they had gone home," but she said she did not know where Ms Macdonald was and "assumed she was fine".
Ms Macdonald jotted her itinerary on an office whiteboard. She wrote: "Ness, Point, Leverburgh - epic car journey."
Lawyer Angus Macdonald, who is representing Ms Macdonald's family, asked: "There was no system which would warn you if staff had failed to return?" Ms Lapsley said: "No."
She said the only system is the whiteboard where staff wrote their destination and expected time of return. She agreed with Sheriff David Sutherland it relied on other staff being around to check the board and their return.
The inquiry continues.