Total time spent learning on Duolingo
It would be cool if each user could have a general idea of how much time they've spent learning a language on Duolingo.
I realize that this is rather difficult to estimate accurately, not only because some learners spend more time on each lesson than others, but also because some learners (myself included) often leave a lesson or exercise open in a tab and return to it an hour later, which would skew timers.
However, I'm sure I'm not alone in desiring a (rough!) estimate of how much time I've spent learning on Duolingo. Currently, the coin system does not give a good idea of time spent. For instance, I speak French relatively fluently and was able to test out of most of the tree, bringing me to level 12 within a few hours. On the other hand, I am a new learner of Spanish and reaching a comparable coin level on Spanish has taken me a lot longer.
Depending on the complexity of the information collected, it might also be useful for the Duolingo staff to be aware of how much time users are putting into Duolingo and where they are spending the most time. (If this is information that is already collected, then please! Let us have access to it!) In particular, if Duolingo were to introduce placement testing as previously discussed, total time spent using Duolingo between tests might become statistically significant.
As a bonus, this might encourage learners not to throw their computer out the window when they miss the last four questions of a lesson, since a failed attempt, while not earning them any coins, would still add to their total time. :)
Thanks for a great language-learning service!