Explain what you mean by half a step?
I'm from a federation in general that favors big movements, we do half steps, but big movement is emphasized. So I might not quite understand what you mean by a half step being sufficient.
Movement within the Universe is relative. We have a mind capable of reducing and expanding a visualization. Time and distance is also relative with Aikido and visualization. We create large spirals, circles and curves, we are also able to visualize them down proportionately and arrive to the necessary Maai. Half a step with either leading or reversing foot, provided Maai is in proportion to the movement as a whole, any technique, Irimi or tenkan will be true.
This is a recent approach O'Sensei dispached when executing his technique. In his later years before his death he reduced his immediate Universe thus reducing exaggerated movements, not because he was a frail old man. O' Sensei always showed the way by example, whether his students captured his example is an other matter. Half a step is his term. I have found Posture and outlook is greatly developed with this understanding. More so its an aquired feeling that brings one to the understanding....Difficult to explain, Sorry.... Yours in Aiki. Chicko.