Kata oyo bunkai must be a key component of karate training, otherwise your kata are nothing more than dances--not that dances are bad, or have no cross-over benefits with martial arts, but they aren't the ideal way to develop self defense capabilities. Unfortunately, the bunkai process can be very hazy, and difficult to navigate and understand. I give anyone putting in legitimate effort to find practical applications for their kata credit, even if I don't necessarily like their results. Iain has a lot of great stuff, and a lot of stuff that I don't like. Either way, the work he is doing is good. There are some general guidelines that you can follow when analyzing kata, about how to figure out what you are doing and what your opponent is doing, but they don't apply to every sequence in every kata in every style. You have to be open-minded about it, in that regard. Still, there are certain principles that are universal in fighting, and there are principles that have been written or passed down by masters of old that we can look to for guidance. Sometimes, these principles are disguised as unrelated bits of wisdom, or as seemingly useless drills, but you can find them if you look for them. Something to keep in mind, too, is that drills related to kata are not always direct self defense applications--sometimes they are simply developing skills that improve your ability to use certain applications. The concepts that are found in the kata, the skills needed to apply them, and the adaptability to change what you are doing if necessary, all have to be developed. Otherwise, you can drill all kinds of techniques from the kata, but if your opponent does something strange or you make a mistake, you could be in trouble.