shouldInterleave static method
Whether the current question index should be an interleaved question.
At ratio = 0.25, roughly every 4th question is interleaved.
Implementation
static bool shouldInterleave(int questionIndex, {double ratio = 0.25}) {
if (questionIndex < 3) return false; // at least 3 on-topic first
final period = (1 / ratio).round();
return questionIndex % period == 0;
}