Yes you can set the individual slide time differently as long as you choose the custom setting on the animation tab for global animation settings (at the very bottom of the drop down). Then further down you will see the element animation and the box for "display slide for" is check marked for Global animation. Remove the check an adjust the time for the slide you have selected and adjust the slide time
The thing is.....when you go custom on the Global animation settings at the top, we lose the ability to use the smooth fade in fade out which I really would like to have as an option. Smooth is only available in the Global settings.
I also discovered that by assigning an id to a paragraph (or most elements) I can then animate the element by changing the animation settings "apply to" for the element selected to "id" then setting the delays and times. Still working with this ....
This is how the 44 animations become available to use to control timing and delays of elements (as in the 3rd slide of the "Present Animated" Template.
I don't design the sites, I make them work.