I'm always surprised by the amount of advises in rehearsal.
I like to give public speaches, but I organize myself completely differently. I spend much time making Slides that are easy to follow and logically ordered, and in each I know that I can say a little more or a little less without disrupting the message. I know that I can count on 1 slide = 1 min. Unless lots of images.
I don't rehearse as I know that I prepared well my slides. Then during the talk I add more or less informations naturally depending on the time left and on the facial expressions of the audience. I usually finish exactly on time.
Usually I read my slides and think about what exactly to say only just before the talk.
I find this way more natural, and less scripted, and I usually get compliments on my presentation and naturalness. I think rehearsing removes much of the naturalness of a talk, unless that aspect is worked extensively, but that could sound a little too scripted for my taste.
One trick that I use often if I tend to forget some information that is important to say, is to put one word that trigger the information IN the slide, but in very light Grey, and in a natural place, like close to an image. So if I ever forget what to say, I have my landmarks in each slide to guide me.
I'm similar. I treat the slides as the skeleton to my talk and I use them to set the pace and go from there. Overly rehearsed talks always feel kind of boring; going off the cuff can have a disorganized awkwardness, but if the slides are decent and the speaker is good enough at explaining them I find them a lot more fun.
I do try and work hard enough on my slides to make sure that the stuff I'm talking about is paced well enough and I do prepare a light "outline" in my brain to remember keep points that I don't want to forget to bring up (that might not be directly in the slides), but most of the words I say are improvised. I don't know if the talks I've given are "good" or not but people generally laugh at my jokes and I've generally received positive feedback at Lambda Days.
I will say, one thing that really helped me become a better speaker was lecturing for two semesters at a local university. I tend to be a very fast talker and have been most of my life, and it's easy for people to not fully hear what I have said (especially if they don't know me very well and haven't adapted to my mannerisms). When I started lecturing, I learned how to force myself to slow down so that students could understand what I said I don't lose them in the dust.
I do almost your method, except I do the presentation a few times as practice to make sure the flow works. When I give the presentation it's not scripted, but since I practiced it is much easier for me to improv. My slides are typically very sparse and simply act as a trigger for which part of the topic I'm speaking on at that time.
But, to your point, I agree that your method is the best way if you know the subject matter. When I practice it's mainly for transitions/flow and not the information.
It’s more like “plans are useless but planning is indispensable” for me. I don’t follow a script when I speak, but the rehearsal sometimes gives me the opportunity to realize when I have trouble articulating something, or it helps me pick and focus on the important pieces of anecdotes so I’m better able to land them in the actual speech.
This is how I present as well.
When what you’re presenting is something you have actual knowledge about, it can be easier to say what you think rather than stress about “sticking to the script.”
True of public speaking just as much as interviewing.
Many people unnecessarily stress about public speaking because they believe the script is the only thing that matters.
Though I admit there is no one size fits all when it comes to speaking.
I often tend to integrate talking passionately about a topic in my head with an imaginary interlocutor. While not directly being a rehearsal in itself, it really helps with developing ideas and chaining concepts - at least for me.
I guess everyone is different in regards to handling the pressure when talking in public, but I do agree that you can feel it, most of the time, when someone rehearsed too "scholarly".
This approach can work for experienced speakers, in particular if you have spoken about the given topic before, but I'd strongly advise against not rehearsing for folks a bit newer into their speaking career. So often I have seen talks where folks either were time after half of their time slot, or they ran out of time towards the end. Or they lost track of the plot, went off on a tangent for way too long, etc.
All this is not great for the audience (who have "invested" into your session, by paying for the ticket, spending time away from work and family, not attending other concurrent sessions, etc.), and it can so easily be avoided by rehearsing.
The most common reason I have seen for folks skipping to rehearse is the awkward feeling you might have when speaking loud all by yourself. If that's the issue, it can help to do a dry run in front of colleagues. In any case, "winging it" is best reserved for later on, after having gathered quite a bit of speaking experience and having spoken about the same, or very similar, topics before.
I'd also recommend to avoid reading from slides during a talk as much as possible, it's also not a great experience for the audience. There shouldn't be much text on slides to begin with, as folks will either read that, or listen to what you say, but typically have a hard time doing both at once.
(All this is a general recommendation, not a comment on your talks which I have not seen)