All original speeches are 10 minutes long, at max. You write and memorize your speech before the tournament, and usually use the same speech for the whole year. Because you write your own speeches, creativity and good writing ability are a must. Original Oratory is a speech to inspire.
Orators are very charismatic people.
They have excellent deliveries and aesthetically pleasing voices. They know how to make people feel good about themselves, and they know how to make others feel good about them. They are good writers, and can keep a speech didactic without being preachy, pleasing without being cutesy, professional without being distant. No real research necessary. Well, it largely depends on what your natural talents are.