Can you adjust a slide duration without dragging the end point?

Robert thank you so much for the video. It helped me, but I had some issues first... My timeline did not want to drag to a smaller amount of seconds, then I went to right-click and set the timing of all of my objects and realised that I couldn't set the timing on groups. I then expanded the groups on my timeline and adjusted only their timing to 10 seconds and only then could I use your method! Hope this helps someone else :)