Hi,
I read the Book once cover to cover and take the full exam at the end(actually ten times).
Yes I see it's not easy to score 80% in the first 3 tests(see my spreedsheet to track my score /note that I'm a french speaker) but after reading the answers I can finally catched it.
T1 72,00%
T2 76,66%
T3 74,00%
T4 89,16%
T5 88,33%
T6 89,16%
T7 94,16%
T8 100,00%
T9 97,50%
T10 99,16%
(I use 9 resources for mock tests:Udemy, Griffiths, Whizlabs)