Study Session Length tells VocabularyShop how much time you will be spent on your study each time. It allows the Study function to make proper arrangement for you.
Every time when you enter Study function, it will create a list of words as a working list for you. Words from that list will be presented to you for study randomly and repeatedly. A word will be removed from your working list when the Study function thinks you have learned that word. A different word may be added to your working list at that time.
The working list usually contains review words and new words. Size of the list and how many new words can be in the list is configured according to the Study Session Length. The list will contain more words and allow more new words in it for longer study session.
Click Settings menu from the menu bar > Study Session Length > make your choice.
The selected study session length will have a purple dot on its left. The default study length is 90 minutes.