Teaching with passion

Seth Godin has an interesting post on teaching that I have revisited this weekend.

“If you teach--teach anything--I think you need to start by acknowledging that there’s a need to sell your ideas emotionally. So you need to use whatever tools are available to you--an evocative PowerPoint image, say, or a truly impassioned speech.”

“If it’s worth teaching, it’s worth teaching well. If it’s worth investing the time of 30 or 230 or 3330 people, then it’s worth investing the effort to actually figure out how to get the message across.”

How much time should youth pastor's spend preparing to teach a message from God's Word? How much time should a small group leader spend in preparation? 5, 10, 15 hours?