Does preparing before a presentation actually help one’s presentation?
My answer to Does preparing before a presentation actually help one’s presentation? on Quora
Yes, in all cases. Not preparing adequately is disrespectful to your audience.
Damian Conway (an outstanding public speaker) suggests a minimum of ten hours preparation for every hour you spend on stage. My own personal experience absolutely backs this up.
Even if you don’t spend ten hours per hour, just one out-loud run through will dramatically improve the quality of your talk, mainly by showing you which bits of it don’t work—so make sure you schedule time to improve it afterwards!