Every transition you add to a slide within PowerPoint has a fixed, default duration. Some transitions such as Cut happen sooner than you can imagine (just 0.10 seconds). Some others like Reveal can take 3.40 seconds to be done with.
To learn more, choose your version of PowerPoint. If we do not have a tutorial for your version of PowerPoint, explore the version closest to the one you use.
Microsoft Windows
Slide Transition Duration in PowerPoint 2013
Slide Transition Duration in PowerPoint 2010
Apple Mac
Slide Transition Duration in PowerPoint 2011
Tutorial Code: 13 08 02
Previous: 13 08 01 Slide Transitions in PowerPoint
Next: 13 08 03 Slide Transition Timings in PowerPoint