When you are attacked the more options you have the longer it takes to decide what to do. The pause while making a decision could be fatal. The actual law is reaction time equals a constant times log base 2 of number of choices plus 1: T = b * log2(n + 1). If you have only 1 response T = b. If you have 2 possible responses T = b * 1.6. If you have 3 choices T = b * 2. The constant, b, varies with individuals and how well the individual is functioning at a given time.
Hick's law predicts that it is best to have one powerful, general purpose technique that can be applied to almost any situation. This minimizes decision making. Another advantage is that you get tremendous practice on your one technique so that you are very good at it. Aikido should be practiced so that all techniques are as alike as possible.
It is also good to have your technique as natural as possible. For this reason all techniques are based on the startle response.