Well again, there are different types of sparring, as well as partner work with striking that might not be classified as sparring, so certainly there can be that interactive training experience without it being simply sloppy freesparring. As far as expecting a student to be around for five years, well I say yes and no. When a person enrolls in a college bachelors degree program, it is expected to take at least four years. If life circumstances interfere with that process and take you elsewhere before you finish, then you don't get a degree. That's life, fair or not. It's something of an apples-to-oranges comparison, I know, but there is some legitimate comparison there. I am of the opinion however, that even if you train for one or two or three years, you should still take away something useful that you have learned. If you did not train long enough to get into certain aspects of training, well that doesn't really matter. You have learned what you have learned, and you can and should take ownership of that, take it with you even after you walk out of that dojo for the last time. In contrast, if you don't finish your degree, you typically don't any credit for it in the workforce. If a job requires a BS in physics, you won't get the job if all you can say on your resume is that you had two semesters of physics at the local university, and then dropped out before completing your degree.