A 16 month course of 6 to 7 hours per day with a lot of exercise and you didn't learn the language at all?
I don't think Duolingo is a good solution but in your case you had all the opportunity to become fully fluent with that kind of regime, it starts to be your fault.
I don't think Duolingo is a good solution but in your case you had all the opportunity to become fully fluent with that kind of regime, it starts to be your fault.