You're still just thinking of how everyone currently uses them. Which I said was the wrong way. None of the uses you mentioned has anything to do with the presentation it's self. You know, the part where you're lecturing in front of a group of people. Knowing how to make a slide deck is all the difference in how useful they are.

What I suggested, flat out, can not be used for anything you said. You might have 70+ slides for a 10min presentation. But it works great during the presentation itself. (What it's supposed to be for). My style guide works for emphasizing points, entertaining and maintaining attention, so people remember more and don't need to reference as much later. It makes the actual presentation better. Not just something to replace notes or reference materials for later. If you're designing your slide deck to actually hand out for people to read, it'll be rubbish for the actual presentation.