Keep in mind that the battery acts as a shock absorber in the charging system. Changes in the amperage flow are not always directly proportional to the alternator output.
Think of the system in terms of water. The alternator is the pump, the wires the pipes or streams and the battery the lake. The pump tries to keep the lake at a set level. If a pipe is pulling from the lake it may take a while for the pump to react and the lake to be drawn to the point the pump begins to refill.
Taking readings at random intervals, while helpful, may not tell the whole story. If detail is needed the readings would need to be graphed in shorter intervals over a long period. Keep in mind that this is just the flow from one point to another and in one pipe. To get the whole story each pipe and its attachment points in the system must be defined. This may be fun to watch , but I'm not sure it would be helpful to the discussion at hand as the system has already been demonstrated to be functioning properly.