Advanced Filters is a feature available on Premium only. You can create custom timeframes to be used for screening Reports, Goals and Alerts. The Advanced Filters settings page is accessed from the Tools menu.
Under Advanced Filters, you'll see the Time Filters tab. Here you can create time filters like the examples below.
Click on the Add a new time filter button where you can create a name for your filter and add/remove the day/times you desire.
Once you have created a filter, it will be available in the date/time selector and the Goal & Alert creation dialogues.
In this example we created "Working Mornings" and "Weekends" filters.
The "Saved Keyword Filters" tab on the Advanced Filters settings page lets you see the keyword filters you have created, and provides links to reports using those filters.