Why is the shot duration extremely high?

You are likely in Live Mode, meaning you're working on a day that is currently "being shot" and shot lister is automatically adjusting your estimated times based on what you have marked as complete or incomplete. You likely have not marked the current shot as complete so Shot Lister is adding 1 minute every minute to this shot's estimated time. Simply mark it and any other shots and notes you have completed as done by clicking the checkmark on the left side of the shot. 

If you'd prefer Shot Lister not adjust times automatically, and not give you an estimate of how far ahead or behind you are, you can turn off live mode by selecting the checkmark at the top of the screen. You can then manually mark shots as completed by swiping right on iOS or Right clicking on MacOS.