If your goal for the sprint is "build widget" then your goal for the day should be "build part 3". You don't change priorities each day, you change how far along you are and where you expect to get to.
The term "Sprint" makes me cringe, it's meaningless in my experience. It doesn't effectively identify goals or deadlines. It's a stupid techie/hipster term that no one apparently pays attention to.
Tried that once as a team. Then it became a derogatory joke word, haven't sprinted since. Well only in real life when playing tag with my kids.
Estimating, delivering on time, working together, can be hard. Someone deciding to rename it with a new label, doesn't usually solve the problem, though now everyone has a new label to make fun of.