When I'm at the final stage of preparation, practicing my presentation, I like to take a day off in between practices to let the content and chronology settle into my brain and embed itself into my memory.
I always felt intuitively that this rest period helped me retain the information better, and now I find that there's research to back up this practice!
There is still not a complete understanding of how our bodies benefit from sleep, but recently there have been more studies confirming that sleep improves the brain's ability to organize and retain different kinds of information.
Here's a quote from one article I read:
"Researchers have uncovered new evidence that sleep improves the brain’s ability to remember information. Their findings demonstrate that memories of recently learned word pairs are improved if sleep intervenes between learning and testing and that this benefit is most pronounced when memory is challenged by competing information.
. . . This work clarifies and extends previous study of sleep and memory by demonstrating that sleep does not just passively and transiently protect memories; rather, sleep plays an active role in memory consolidation."
This article talks about how different stages of sleep preserve different types of memories:
"Sleep apparently rearranges memory within the brain. 'We presume that it's organized into a more efficient storage location,' Walker says. 'That means you can recollect that information the next day much better than the day before.'
Sleep has this effect only on procedural memories, that is, memories associated with a physical procedure such as playing a piano or riding a bike. These memories are normally used without conscious effort for motor skills that can't readily be described in words. Furthermore, it's only light dreamless sleep that works this magic.
By contrast, deep dreamless sleep consolidates, or crystallizes into long-term memories, newly formed declarative or episodic memories, such as what you had for dinner yesterday or the fact that Paris is the capital of France. Sleep stabilizes these memories and prevents them from decaying over time."
This is just one more reason not to wing it, and to give yourself plenty of time to practice, so you can have "off" days and enough sleep to let your presentation sink into your memory.