The galvanic scale is the electrochemical scale that has been heavily simplified. If you can work with the electrochemical scale you can predict rates of corrosion between elements in a bimetallic circuit through knowing a measurable amount of potential voltage.
It is like the model of the atom is taught to many as being a nucleus with a set of circular rings of electrons, which slowly build up along the period as more electrons are added known as the bohr model. Although not wrong its not the complete structure and its simplified nature leads to it being restrictive.
Actually the electons have a precitable field of movement although it is said to be impossible to say where an electron will be at an exact moment around the atom, orbitals can be used to predict the area in which the electron is most likely to be. The atomic structure changes between elements much more radically and is not always linear there are some electrons that drop the energy level from there systematic orbital in favour of a more stable atom. This is a more accurate model of the atom which is widely accepted