Hello Matthew,
I have searched through many blogs and finally ended up what Mahboob suggested which looks to be more stable.
Here's the code for that. Just replace the [Date1] with your later date and [Date2] with recent date and you are done.
=DaysBetween(RelativeDate([Date1];Floor(DayNumberOfWeek([Date1])/6)*(8-DayNumberOfWeek([Date1])));RelativeDate([Date2];Floor(DayNumberOfWeek([Date2])/6)*(8-DayNumberOfWeek([Date2]))))-(Floor(DaysBetween(RelativeDate(RelativeDate([Date1];Floor(DayNumberOfWeek([Date1])/6)*(8-DayNumberOfWeek([Date1])));(DayNumberOfWeek(RelativeDate([Date1];Floor(DayNumberOfWeek([Date1])/6)*(8-DayNumberOfWeek([Date1]))))+1)*-1);RelativeDate([Date2];Floor(DayNumberOfWeek([Date2])/6)*(8-DayNumberOfWeek([Date2]))))/7)*2)
Regards
Niraj