Examining the relationship between ABCmouse usage and performance, the metrics most significantly related to overall posttest scores (literacy and math combined) were average days of gameplay per week, average activities completed per week, and average time spent per week. Figures 1, 2, and 3 show that using ABCmouse for at least 45 minutes and completing at least 15 activities across at least three unique days per week is associated with greater improvements in key math and literacy skills. In other words, more time spent engaging in ABCmouse is related to higher posttest performance.
You can view the full research here: ABCmouse Research Brief