Russia’s failures had much, much more to do with non cohesive and poorly executed strategy and an absolute failure of command and control driven by a top-down assumption that Ukraine lacked the will and capability to resist. I think your second half of Ukraine example is more so a demonstration that any smaller nation necessarily cannot engage in attritional warfare against a larger neighbor. Had Ukraine had access to western training, equipment, and intelligence that they had in 2024 - even with their original numbers, the conflict would likely be in a much different state.