Order of the subshells in an electron configuration
Whilst the said concept is correct, as orbitals increase in number the less they are attracted to the centre of nuclei, consequently the further they move away the higher the energy they possess.

The 2s electrons spent more time closer to the nucleus (when compared to 2p electrons) and this reduces the energy of electrons in s orbitals, the nearer they get, the lower the energy. This is why the s orbital always has a slightly lower energy than p orbital at the same energy level.

The 2s, 3s .... orbitals get progressively away from the nucleus.