Just an idea
Why don't they make a section where you can see you percentage of you marks and you successful lessons I would be helpful to see which lessons you are weak on. On some lessons like the basics, it tells me I need to practise, but I know these already It might just me but I like things to be really clear
You can see all your learned words in Vocabulary and with Strength you can see them from weakest to strongest, so you only have to practice the weakest ones. You can also practice one word at the time by pressing the word you want to practice, this method is good for verbs.