Repetition of topics and subtopics is by far the most important part, reinforcing attention on the topic at hand even if the text in the chunk appears unrelated to the topic when viewed in isolation.
Keeping the indentation is also important because it is an implicit and repeated indication of the nesting level of the content that follows. LLMs have trouble with balancing nested parentheses (as the sibling comment to yours explains).
Dealing with text where indentation matters is easier for LLMs, and because they have been exposed to large amounts of it (such as Python code and lists of bullet points) during training, they have learned to handle this quite well.
Keeping the indentation is also important because it is an implicit and repeated indication of the nesting level of the content that follows. LLMs have trouble with balancing nested parentheses (as the sibling comment to yours explains).
Dealing with text where indentation matters is easier for LLMs, and because they have been exposed to large amounts of it (such as Python code and lists of bullet points) during training, they have learned to handle this quite well.