Some people script out their entire message. Some people are even successful doing it that way. But most speakers lose far more than they gain by preparing exact wording for an entire speech. Craft and shape your opening and closing, but don't fall victim to scripting the whole thing. As a pilot, you plan and execute with precision your take off and landing, but once air borne know how to enjoy the ride taking people to the locations they want to see. Once you are soaring on the wings of words, don't be trapped by the words you have deposited on any page. You don't take cue cards to a party. Prepare, but make your presentation a party for all involved.
Speak from you passion and preparation to serve in the moment. Look into their eyes. Come from experience and make sure you and your audience enjoy the ride. Keep an eye on the fuel gage and when the clock says you're nearly out of time, go back to that targeted and prepared close. Don't be a slave to a speech when everyone wants to soar along with you!