IMO, preparing for some generic "physical confrontation" is a waste of time, exceeded perhaps only by preparing for a confrontation that comes straight out of a comic book or a bad martial arts movie and that will never happen to you in real life.
I disagree. It will happen if you go looking for it which begs to ask, why look for it?
If you have to "prepare" for a fight, you don't stand a chance. You learn things for yourself. You are in tune with your body. Know your limitations. When a true fight breaks out, they never go according to the plans you lay in your head. I know very little when it comes to Aikido but maybe I will use an example anyway- Think of doing roundori. You can't plan exactly what move your going to use when and what direction you're going to go in. You go with the flow.
Prepping for a fight is the wrong attitude to have. Prepping yourself and being the best you can be is the right one to have. Then there is no think if the time should come, there is just do.