Good communication should have multiple intermediate levels of detail. To give a very powerful presentation, our first instinct is often to barrage our audience with data. This has the opposite effect, as The more visual detail presented on the screen, the more likely your audience will experience cognitive overload and tune out The skill is in focusing the message into a single point. This is similar to the idea of the Snowflake Method in writing.
The three-minute story is your entire presentation distilled down to three minutes. Even if you have 20 minutes to give the presentation, humor yourself with the exercise of getting rid of anything non-essential and get it down to three minutes. You can always expand later.
You can take it a step further and narrow it down to 30 sections by focusing on the big idea. The big idea is the point of it all; what you want your audience to do and why.