I'm thinking that the JT610 P1 retrimmed completely from each MCAS excursion, but P2 did not allowing the nose down trim excursions from MCAS to accumulate while P1 was head down in the manual - which had no information on MCAS.
Will the CVR, once released, show whether P1 communicated to P2 what P1 was doing with trim before handing over control?
Remember also that stick shaker was adding workload.
We now know that a faulty AoA will both trigger shaker and MCAS once at a safe height where flaps are normally retracted and more thorough diagnosis of the situation can begin, but then they were handed a new problem.