Spiral springs are used as torque generators for smaller angles of rotation.
The stored force serves as compensation or retraction torque, the torque/angle of rotation characteristic is almost linear.
The angles of twist allowed for spiral springs are usually small.
The working range should be in the middle area of the example of a characteristic curve shown below,
in order to keep the contact between the coils to a minimum and achieve an almost hysteresis-free characteristic curve.