even though you set your start and end times you have to go in exactly at those times and confirm or the clock keeps running, quickly making your entire schedule way inaccurate. The app needs to just switch to "start fast/end fast" on its own at the predetermined times, and push a notification letting you know, with the option to indicate when you're extending a mode. instead it took a whopping 2 days before mine is more than 15 hours off, making it pointless. :(