LearnScripture uses the principle of spaced repetition to plan out the review and testing schedule for your verses.
After you have initially learnt a verse, it will come up on your dashboard for review within a few hours. It will then appear again after about a day, and you'll see it about 5 times within the first week. Then the gaps will keep increasing, until the verse is considered fully learnt after about 1 year, at which point it is retired and not tested any more.
In addition, LearnScripture uses your test scores to adjust the review schedule — if you score less than 100% for a verse it will be adjusted so that you see it again sooner, and it may take longer to reach the 'fully learnt' stage.
According to various studies, these gaps are an important part of the learning process.
For passages, the review schedule is adjusted a bit, to help you learn the flow of the passage rather than individual verses.