blog-post-twenty-rules-of-formulating-knowledge
https://www.supermemo.com/en/articles/20rules
Repetitions of simple items are easier to schedule... If you consider an item that is composed of two sub-items, you will need to make repetitions that are frequent enough to keep the more difficult item in memory. If you split the complex item into sub-items, each can be repeated at its own pace saving your time.
^repetition-of-smaller-items-easier-to-schedule