If you have a report in workspace using an event, something like product views as your metric and week as your dimension, and you see a drop in views in the last week and you want to see which day that started on, you would break it down by day. However, when breaking down by day, it will give you a list of all days in your time period, not just the days in the week you are breaking down, like this:
I don't understand why this would be the case. I would expect to only see the days in the week I am breaking down.
One thing to note, when I do that same type of report but use a standard metric (like visits, page views) then this issue doesn't happen (I only see the days of the week I am breaking down).