Once you select an animation, a pop-up will appear with presets already applied. In this case of Fade In, you will see that it will fade in over .75 seconds and has a delay set to none. Also, the animation ease is set to Expo Ease Out. Defaults are set for each animation type and also their trigger. For instance, the default for Scale In for the Page Load trigger is different from the default for Scale In for the While Hovering trigger because the intent and experience is different.