Hey!
Here is my experience regarding those exams.
I'm converting my EASA (Europe) ATPL into Canadian one. I fly for European airline with +7khrs on A320.
I just wrote SARON, SAMRA and INRAT 3 days in a row.
I had to squeeze reviews between work and family time. Was not that easy.
I spent a total amont of approx 100h in the last months trying to understand CARs and specificities of those written exams.
As time was limited, I intended to focus on passing, not having highest marks possible.
Culhane ATPL books from 2018, TC AIM and Nizus 1 months subscription were my sole materials. At first, training marks were low (50-60%) but increased slowly with time. I went to write exams with training marks between 65 and 80.
I was happy to notice that exams were quite similar from those of Nizus. Maybe questions are sometime a bit trickier in real exams, but still doable.
I passed all 3 exams with marks from 84 to 92.
TC AIM vas very useful. And nizus tests enables to know on which parts reviews should be emphasized.
Happy flights!