nice app btw...
I wanted to propose a new feature, like a rating system.
It shall give you points for your learning progress on each separate deck. It would be possible to compare decks regarding difficulty and thereby adjust settings (intervals/multiplicator) or learn about one's strengths and weaknesses in order to dedicate more time/attention to the ladder. And it might be interesting to know. So it should serve for several purposes, so there should be various algorythms for calculating different kinds of information.
Sometimes when I go through a lot of cards and make many mistakes, kicking cards on stage 10 back to 0, I wonder, if this session wouldn't be rather contraproductive. Of course I learn something, but you know... I could use some hard information to tell me to try a little harder.
But after thinking for a while, it occurred to me, that this would be rather difficult.