The Checks and Balances of Presentations

In preparing for a presentation which I will deliver tomorrow, I have noticed that there are these very interesting relationships around expectations. If I form a very strong image of those to whom I am presenting, I will often feel surprised or often disappointed when the things that people do turn out different from my 'image'. In fact, what actually happens is often, if not always, different from how one imagines it, because there are so many unforeseen conditions that influence the way a particular presentation is going to unfold. If one were to actually 'fathom' the factors that influence the look and feel of a presentation, I am sure it would be quite mind-boggling to behold.
    Why, then, does one need to prepare for a presentation if there are so many unforeseen factors? Well, this might be along the lines of asking, why does one need a train track when so many unexpected hazards will cross the tracks? Of course, one needs a path or a track, to make the train work and allow it to accomplish what is needed. But if the fixation is on the track itself rather than on the whole journey that one makes, then everything will seem like a jolt to the train's path. In a similar way, one needs to have some kind of a plan for how to organize a discussion and what to teach. I see it as the dialectic between the speaker and the listener. If I am only speaking to hear my own voice, then the listener will feel totally excluded from the unfolding process of learning, and it will seem a waste of time for the listener. But if the speaker is able to organize her or his thoughts according to the situation of the listener, then the presentation becomes a good fit, and the learner's needs are considered.
    Imaginatively,  I picture a presentation as a bit like what an artist does when she or he paints. I have once watched a television program when I was a teenager where an artist paints, then stands back to look at what she or he has painted...then paints, then stands back..repeating the process back and forth until satisfied with the unfolding view of the picture. If I am not checking in now and then to see how the picture might look from a distance, from another angle, or in another's place, then the picture only becomes a monologue, and I am not able to see if from other perspectives. There is a careful straddling here between sticking to one's purpose and allowing other purposes to influence the direction.