The varied nature of 2D materials has defied facile classification thus far owing to the numerous atomic structures and the myriad arrangements with which bonded layers may nestle together. However, the poor bonding in the interlayer direction should always be observable in the electronic band structure of the material; see for example the band structures of the archetypal 2D materials WSe2, MoS2, WS2 and MoSe2 in Figure . The curvature of the bands is known to correlate with degree of bonding and each of these materials has a noticeable contraction to flat bands in the specific path of the Brillouin zone that corresponds to the interlayer crystallographic direction. This band curvature is often quantified or expressed as conductivity effective mass; with positive (p-type) charge effective mass arising from the curvature in the occupied valence bands and negative (n-type) charge effective mass arising from the curvature of the unoccupied conduction bands. These days, publicly available codes and open-source software exist that can calculate the conductivity effective mass automatically and indeed have already been deployed on repositories of many thousands of materials. In this paper we assess whether such automated analysis can recover the likelihood of 2-dimensional nature of a material based on the conductivity effective masses arising from the band structure by calculating the exfoliation energy of the two thousand stable materials reported to have the most anisotropic conductivity effective mass tensors.