For talks to user groups where I'm generating new slide decks and demos one piece of advice I was given was reckon on around 1 hour of prep for each minute of s

For talks to user groups where I'm generating new slide decks and demos one piece of advice I was given was reckon on around 1 hour of prep for each minute of speaking time. The successful stuff that I've done seemed to match this. Also for a one hour time slot you'll probably actually want around 40 minutes of material allowing time for introductions and a Q&A session at the end.