Day Parting is also known as Ad scheduling. It helps you to select particular times of a day you want your ads to be displayed. By doing so, you can maximize performance by increasing the visibility of your advertisement.
If you are a B2B marketer and you are aware that there are only specific hours when maximum searches are done, you can make sure that your ads get displayed in that time. It avoids paying for no output.
It also enables you to get ahead of your competitors, if they exhaust their advertising budgets in absence of proper planning. It increases your ad position and reduces the CPC to your benefit.