How long does it usually take you to prepare a presentation?
My answer to How long does it usually take you to prepare a presentation? on Quora
Damian Conway (one of the best technical presenters I’ve ever seen, who also runs amazing tutorials on giving great talks) says “to produce really top-class presentations, budget at least ten to twenty hours per hour of speaking”.
The more experienced I get at public speaking, the more I agree with his rule of thumb.