There is lack of understanding and measurements for the conflicting migratory aptitudes of Hydride in Pinacol-Pinacolone rearrangement.
In an authentic chapter written by Bruce Rickborn of University of California, I remember reading that migratory aptitude of hydride is same as that of phenyl in Pinacol-Pinacolone rearrangement.
If not equal, it is believed that migratory aptitudes of Ph and H are very close. This leads to concept of reversibility and complications relating to kinetic v/s thermodynamic control in case of di and tri-substituted vicinal diols. Often aldehydes are formed as kinetic product, but more stronger conditions ( concentrated acid, higher temperature ) produces a phenyl-ketone conjugated system as the thermodynamic product.