Determining correct exposure with precision is a challenge to any automated system.
For experienced photographers, there is no substitute for taking more or less full control of the process.
Unfortunately, this requires not only skill, but it takes time and careful attention to detail.
However, not all work is hurried and, even with digital photography, precisely correct exposure always saves time and work later.
For much studio photography, taking an incident-light reading is a much-favoured technique for determining exposure.
The light-sensitive cell of a hand-held meter is covered with a translucent white hemisphere that collects light from a very large area.
The meter is held at the subject position with the hemisphere pointing toward the camera.
Thus, the meter integrates all light falling on the subject to arrive at a cumulative average.
The meter cannot distinguish between one side of the subject being in shadow while another is in bright light; it simply adds the two together.
It also takes no account of the nature of the subject itself, which could be dark and absorbent or bright and reflective.
The meter reading would be exactly the same.
The advantage that this method has over a reflected light reading is simplicity; and it always provides a good basis for bracketing exposures.
However, you do need to move from the shooting position to the subject position, which may sometimes be difficult.
In addition, small differences in the meter position can make a big difference to the reading, facing you with the problem of deciding which is the "correct" reading.
Incident-light metering is, therefore, most useful where bright light is falling on the subject from the side or from behind the camera position; it is tricky to use in backlit situations.