Daren,
In a word: yes. If a person never progressed beyond Mod 1 they would have a pretty formidable system. Having said that, however, it is important to go through the entire program. The thing that makes SDTS so powerful is that it is NOT really technique based. No, the true power comes from the fact that SDTS is philosophy based. What I mean is that it is Damian’s way of looking at things — his principles — that holds all the secrets. For example, “Lead with speed, follow with power.” Or, “Don’t chase the weapon, attack the man.” If technique was all that, we’d all be friggin’ Bruce Lee! 
A punch is a punch and a kick is a kick. Every martial art or system has pretty much the same moves more or less.
Sure, [Damian Ross] is going to teach you some “moves”, but as I’ve stated elsewhere, he’s not really teaching you anything that your body won’t do instinctively anyway; he’s just given all your fight or flight reactions names so we can communicate with one another and train. Only by learning principles, not just technique, will you be the most effective. And to do that, you gotta hit all 12 Mods… there’s gold in every single one. 
P.S. Don’t forget to get some basic equipment and work the drills, too. Watching the video entertains, drilling the video trains!
Good luck and stay safe.
