And this person seems very comfortable using it which would mean they use it regularly...again the type of work performed in the area or at her house could be helpful in narrowing some things down.Only thing about mechanics habitually using mouth lights is that they have many metal surfaces to mount magnetic lights on, and typically use those instead (in my experiences with them generally and in working on cars sometimes myself).
However, HVAC, electricians, plumbers, pest control, etc. would likely need a light like this in the atypically visited and cramped locations they often find themselves around a home or business.
JMO.