Course: English
Level: 50
Platform: Windows PC
Browser: Firefox 57

First of all, I thank you all for this amazing tool to learn languages; I really appreciate all your effort to make it available for all of us, the users. I like the structure of the sentences and the level of words used.

Additionally, I'm writing to bring some concerns to your attention.

Supposedly the English course has 5013 words/sentences, but as far as I understand the Lingvist algorithm 'adapts' to our language level and trains us accordingly. In other words, we will see just some words/sentences from the big pool available. According to my statistics, I've seen 3410 words/sentences from the 5013 available for practice – just a 68% – and I've not seen any new words for 10 days because according to the algorithm I'm 'done' with the course (Level 50), and I don't need to see all those words/sentences that the algorithm chose to skip. Thus:

Are not missing too many words/sentences from this big pool available?

I could ask for my account to be reset, but probably I would end up missing the same amount of words/sentences, unless I intentionally fail each sentence at least once.

Furthermore, the algorithm is in a loop with my most recent mistakes and isn't giving me old sentences. Explanation; fifteen or eleven days ago I did a mistake with the words Rally, and Rocky in two separated sentences (only one mistake per word), but it has been giving me those two sentences almost daily since: 9 times for Rally, and 8 times for Rocky. On the other hand I haven't seen the word Comprehensive for around a month (before that I practiced 6 times), and that is a word that it took me long to master.

Keep in mind that I'm not complaining, I'm just sharing my data, which I hope is useful for your internal analysis.