The local thermodynamic equilibrium assumption, i.e. the liquid/vapour interface is at saturation temperature, is widely adopted in modelling evaporation processes. Undoubtedly, it serves as a convenient way to bypass the detailed evaporation kinetics. However, it is known to be conceptually incorrect, as net evaporation can only occur when the interface is out of equilibrium. The question then arises: how much error does this assumption introduce, and how can it be corrected when it breaks down? This talk will briefly delve into the physics underlying the evaporation process in both pure vapours and inert gases, before outlining potential approaches to count for the out-of-equilibrium evaporation kinetics. Results on two simple practical configurations - one on the evaporation of a flat thin-film and the other on a spherical droplet - will then be presented to quantify the validity of the local thermodynamic equilibrium assumptions.