After a learner increases their mastery strength, there is a waiting period before they can increase it again. This leverages the concept of spaced repetition, which prevents learners from reaching their target mastery strength through short-term cramming. Instead, learners must demonstrate proficiency over time, which leads to long-term retention.  ProTip: When information is retrieved over time, the brain starts to recognize that it is important and is worth storing for future use. This is how information gets moved from short-term to long-term memory. If a learner's target mastery strength for a Concept is level 5, the fastest they can reach this target is in a week. However, we recommend that you set your learner's target strength to level 3, as the system will naturally have your learners reach level 5 over time.