Requiring two dives makes no sense to me. The course is mostly academic with a few practical skills such as the O2 check and checking the checker..
If someone can explain why there is a NEED for two dives, I'd like to hear it. Again, if you say it's because you're evaluating diving skills.. well then, that should have been done in another training segment. If I'm paying to learn about nitrox, that's that I want. Now if you're (the instructor) are willing to dive teach me something new I'd be OK with it, but again, that is outside the scope of learning about nitrox. Am I missing something? If so, please explain it to me.
Is SDI the only one not requiring the two dives?