Redwood Timecard red line week separator

Hello, what exactly represent the red line separator on the Redwood timecard? We are using Monthly timecard period and i would suppose that this red line will simply shows week start. But for some reason it simply appears after 7days, so if the month starts with Wednesday, then the line is on Wednesday, which doesn't make sense.

Is this some feature or bug ?

If feature, can we somehow influence where it shows? To have it always on Monday?