I didn't see any discussion of strategy or leadership in the Book of the Five Rings.
I have, however, seen many cases in competitive gaming where correctly judging what my opponent was expecting me to do allowed me to counter them more effectively. There are a large number of meta-levels there, and operating two levels above your opponent is typically as bad as operating one level below them.
The principles of strategy are written down here in terms of single combat, but you must think broadly so that you attain an understanding for ten-thousand-a-side battles.
It appears to me that Musashi intends his principles to be applicable to either duel or battle. There are several illustrations that imply that he is not just talking about duels:
...First, in large-scale strategy, when the enemy first discharges bows and guns and then attacks, it is difficult for us to attack if we are busy loading powder into our guns or notching our arrows. The spirit
Once again, here's the new thread for posting quotes, with the usual rules:
Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)