Here's something that has been bothering me for a while.
As I keep unlocking new drills, I keep running into words which I have already mastered about a hundred lessons earlier. I personally find that annoying, as it keeps flooding my already overflowing drill-schedule with duplicates of entries which I already mastered months ago.
If the point is about making sure that you still remember the drills a few months later, then I suggest expanding the drill intervals - this would also alleviate the issue of having too many drills due at a time if you progress through classes at a steady rate of, say, a lesson a day.
And I mean, let's be honest. What are the chances that anyone is ever going to forget "かわいい"? So then why does it once again get added as part of the drill set #196?