This can help track how long did an activity last, For example driving to work. You can create a “Driving” duration button. Click on the duration button and it will start counting in seconds. When the button is clicked again the counting stops. Duration of driving is logged in the history.
Similarly you can monitor how long your kid watched TV. Create a duration button and click the button when your kid starts to watch tv. Click again to stop the counter. You can go to history to see all entries or see a graph of all entries. If you own an Apple Watch it is even more convenient to start and stop the duration button. Total and averages of your entries over days , weeks or months are shown on the phone and the watch.