Is there a way to change the time intervals on the time ruler? For example, I want each slide to display for 6 seconds. Right now, I'm dragging each slide until the indicator registers "6." This is quite tedious.
You can zoom in or out until the spacing is 2 seconds, in which case you can snap the image events to fit 3 marks on the ruler.
Probably better yet is to go into Options / Preferences / Editing and set "New still image length" to 6 seconds. Then you won't have to adjust them at all.
Options - preferences - change the default image length to 6 seconds. Then they will all automatically be 6 seconds (instead of the default of 5).
Alternately you can use scripts to change the length of images. This is useful if you already have a bunch on the timeline and wish to change their lengths after the fact.