When is rehearsing a presentation a bad idea? Clients often try to talk themselves out of rehearsal, because they’re pressed for time, because they don’t like the feeling of rehearsal (you’re not in control yet), or because they argue that rehearsal will make them stale.
Those are bad arguments. People who ‘wing it’ usually betray their lack of preparation in their body language. They don’t think they do, but they give themselves away. So generally, more rehearsal is better. But there are times and kinds of rehearsals that are counter-productive. Here are 3 ways it doesn’t pay to rehearse.
Don't rehearse more than once on the day of the presentation.
I can imagine exceptions to this rule, but not many and not often. By the day of, most people are in adrenaline mode, and rehearsal is not very helpful. Do rehearse once, especially in the actual venue, just to get familiar with things and have the performance fresh in your mind. But obsessive rehearsal at this point simply won't do much good. You have to have done the work already. It's too late.
Don't rehearse the wrong speech or presentation.
This may sound odd, but you'd be surprised how many times people don't have a speech set until the last minute, so if they do rehearse, it's the 'wrong' speech — because it's not the one they're ultimately going to give. Get the speech set, weeks before the date, and rehearse that one. Many people get nervous as the awful date approaches, and they start to doubt themselves and the message. So they tinker with the speech, almost always making it worse. Don't fall into that trap.
Don't rehearse too often only in your mind.
Half the reason for rehearsal is that speaking, like, say, acting, is a physical art. You rehearse so that your body can learn the speech, not just your mind. Too many people say, "I don't need to rehearse, I ran over it in my mind." Therein lies potential disaster. You need to discover physically what it feels like to give the whole speech, to say a particular line out loud, to make the transitions from one section to another. None of those things can be imagined as effectively as they can be rehearsed.
How much should you rehearse? A lot. Stage actors often get up to 6 weeks, 5 or 6 days per week, 8 – 10 hours per day, to rehearse. That's how you end up looking natural, assured, and authoritative. Not by winging it.