Both have their own merits. Variety enhances the traditional translation to the field as the actual field encounter, situation, personal anxiety and quarry behavior and shot and may likely be still quite different from the simulated practice.
Stumping and 3D both require intent focus while 3D has you address the animal’s vitals. Many 3D vitals for the shot required for score are not accurate in a live field situation for the particular angle, yet 3D’s still raise the awareness.
Believe both are quite beneficial and in personally choosing one over the other remains with the individual prerogative.