Partner exercises teach and display some techniques better than individual exercises.
Virtually anyone with ten minutes of sword training could cut an unarmed opponent, Seisan or no Seisan. Never mind a kendo artist. An improvement would apply the throw to the sanchin steps and strikes in the beginning, not middle, of the kata. Kanshiwa Bunkai suffers from similar flaws. The waukes and bushiken strikes, excluded from the four person form but found in versions of the two person form, suffer similarly.