When I was teaching, I stuck with the material that was part of the curriculum- (the tradition). If I was working with someone outside of the class, then I'd tend to gear it more SD.
There has been a huge debate reagrding the cross training topic, and what is and what isnt included in the teachings. IMO, if you are interested in learning a teaditional art, thats fine. If you are concerned with SD, the learning something that is simple, quick, and to the point, is the best route to go. Also, making sure that you are training with aliveness and resistance, you will find that you will get the most out of your training.
I have watched alot of classes and have seen how many of the people train. 1 person throws an attack, and the other one defends. Thats it!! Is that how its going to happen in real life?
Do I think that my main art (Kenpo) contains everything that is needed? NO! There are many pricniples that are not included, which are very important. Why are they left out? Who knows. Maybe people think that they are not important. IMO, standing in a stationary stance, throwing punch after punch and kick after kick, is not going to help you. You need to train with some movement.
I'm sure that there will be some that disagree with the above statement, and some that agree. Again, I"m speaking for myself and the way I gear my training.
Mike