It really is something that you need to discover for yourself. There are all kinds of different approaches to every aspect of stage management, and it's important to learn what's best for you and your company.
HOWEVER...I must say, in all fairness, that when you are first starting out as a SM it can be very difficult to break yourself from the "Am I doing this right?" mentality. It is something that I struggled with quite a bit when I first made the transition into my collegiate theater department (I had stage managed in High School and because some of my techniques were different than those of my peer SMs, I though I was wrong. As it turns out, some of my stuff actually works better than theirs). So, moral of the story....be thorough and prepared, but don't think so hard that you drive yourself nuts over unnecessary minutia. Take the time to grow and learn while doing your job to the best of your ability..
But, if you really want my opinion, I think you would be better off with more than one stage diagram from each bit of blocking/dance. Milliehas WAY too many people on stage dancing at once for a single diagram. When I SMed the show in HS I didn't even use a ground plan, I just wrote copious blocking notation in my script and never had a problem with it. Like I said, do what works for you, but I think you're on the right track.