What type of control defines the efficiency of the modern gas stove?

Instantaneous control

The modern gas stove represents a distinct category of efficiency champion compared to solid fuel devices because its primary advantage is usability and precise regulation, achieved through instantaneous control. When a gas burner is engaged, the user can immediately adjust the output level up or down, providing extremely tight regulation over the exact amount of energy being applied to the cooking vessel at any given moment. While its pure thermal efficiency might occasionally be lower than a perfectly tuned modern biomass stove, the efficiency in terms of use—eliminating the need to start a fire, generating no residual ash, and offering precise metering of the natural gas fuel—made it highly desirable.