I'm wondering how she told you to take the 4X7.5 and 3X10?
If you take 7.5,7.5,7.5,7.5 and then 10,10,10, I would expect to see some variation in INR depending on what day you test.
To minimize the variation, it would be best to take them as follows
7.5, 10, 7.5, 10, 7.5, 10, 7.5 on S M T W T F S