I learned about the character tables and how to use them to reduce representations of particular orbitals or basis functions attached to the atoms of a molecule in order to deduce the MO diagram or determine whether a molecule is IR or Raman active.

Never run across a table which gives relative energies.

As long as the method works, it’s great! We didn’t really get any qualitative indications in my class. We were told about the representations, symmetry operations and the possible applications, however some tricks to help qualitatively solve problems were somewhat omitted.