driving a 3 phase locomotive needs special training, as their controlling (which is VVVF based) is much different than the single phaser (which are tap changer based) ones. Just because neighboring shed has WAP7 doesn't mean you'll see them soon.
And loco individually may not make much difference, if the train has no sectional priority. A rajdhani with a WAM4 is more likely to reach on time than M/E with WAP7