In a recent paper [Physical Review B 100, 075412 (2019)], A. Díaz-Fernández et al. propose to Floquet engineer Dirac cones at the surface of a three-dimensional topological insulator. They show that a large tunability of the Fermi velocity can be achieved as a function of the polarization, direction, and amplitude of the driving field. Using this external control, the Dirac cones in the quasienergy spectrum may become elliptic or massive, in accordance with experimental evidence. These results help one to understand the interplay of surface states and external ac driving fields in topological insulators. In this work they use the full Hamiltonian for the three-dimensional system instead of effective surface Hamiltonians, which are usually considered in the literature. Their findings show that the Dirac cones in the quasienergy spectrum remain robust even in the presence of bulk states, and therefore, they validate the usage of effective surface Hamiltonians to explore the properties of Floquet-driven topological boundaries. Furthermore, their model allows us to introduce out-of-plane field configurations which cannot be accounted for by effective surface Hamiltonians..