For unique criteria, if the start and end date (workdays only) is more then 7 then count

I need to count the number of times it took over 7 workdays to finish a unique document.

For example using the data below, the number returned would be 2.
(It took over 7 workdays to finish 2 documents [Onboard manual and Computer Use]).

I am currently using this formula to count the number of unique documents:
=SUM(IF(FREQUENCY(IF(LEN(C$2:C$10000)>0,MATCH(C$2:C$10000,C$2:C$10000,0),""), IF(LEN(C$2:C$10000)>0,MATCH(C$2:C$10000,C$2:C$10000,0),""))>0,1))

Thanks in advance!


Start Date End Date Document Name Mis
03/18/2013 04/18/2013 Computer Use 54
03/18/2013 04/18/2013 Computer Use 65
03/18/2013 04/18/2013 Computer Use 35
03/18/2013 04/18/2013 Computer Use 44
03/01/2013 03/18/2013 Onboarding manual 3
03/01/2013 03/18/2013 Onboarding manual 1
02/05/2013 02/08/2013 Training 1
02/05/2013 02/08/2013 Training 2
02/05/2013 02/08/2013 Training 21
02/25/2013 03/04/2013 Odd document 231