Default media insertion behavior of "show until the end" can create extra work...

I often have didactic explanation of processes or concepts, and have media appearing and disappearing based on the voiceover captions. What makes me a bit annoyed is that the default behavior is to display the media for the entire slide length. So, if I insert a 20 second video clip into a 4-minute slide, I have to make the timing work out. The same thing with pictures... I want to display a picture for 30 seconds, I insert it, then de-select "show until the end," and then drag the picture timeline to where I want it.

It would be nice if there were an option in the "import" button for pictures or video, a checkbox where one could define if the media should be for the entire timeline of the slide or not...