Okay, I get it now. Here's an example.
Sitting 1 - 10 days
Unit 1 - Pass
Unit 2 - Pass
Unit 3 - Fail
Sitting 2 - 10 days
Unit 4 - Pass
Unit 5 - Pass
Unit 6 - Pass
Sitting 3 - 10 days
Unit 7 - Pass
Unit 8 - Pass
Unit 9 - Fail
Sitting 4 - 10 days
Retake Unit 3 - Pass
Retake Unit 9 - Fail
Sitting 5 - 10 days
Retake Unit 9 - Pass
PASS.
6 Sittings of 10 days each. Units can be divvied up in to those sittings but you cannot retake a failed unit in the same sitting.