In French, there are two ways to refer to the amount of time we, in English, refer to as a week. First is the straightforward "une semaine" or "one week." However, in conversation it is more common for people to refer to a week as "huit jours" or "eight days." Now if you count the days, from say Wednesday until and including the next Wednesday, you will count eight days. I don't know if this is the logical origin, but if someone, on a Friday, says they'll see you in "huit jours," show up at the specified time on Friday, not Saturday.
Similarly, "quinze jours" is equivalent to two weeks (or a fortnight), and not the two-weeks-plus-one-day that you may expect. Lauryn, however, has her own non-French, non-"English" way of counting days.
She eats breakfast 14 times a week, and never has dinner/supper. Each one of our days is, in Lauryn's world, comprised of breakfast, lunch, nap, breakfast and another (long) nap. Consequently it has been very challenging to teach her the concept of "days of the week."
However, while she knows that once it gets dark at night its time to go to bed, she doesn't fight the afternoon nap despite the fact that its not dark. No complaints here.