Why do I need to wait for reviews.
At my kanji App, we use a spaced repetition system to help our members study kanji. This means that when you have finished your lessons, you'll have to wait till the next items come available. The goal from a spaced repetition system is to give you a review right before you are about to forget something. By doing this, your brain finds it more relevant to memorize the current item.
To minimize the amount of time that you need to wait between reviews, we recommend that you do all your lessons and reviews as soon as they come available. If you do things right, you will be unlocking new items within days or even hours. At your dashboard, you can see how long it takes until your next set of reviews are available.