When facing new subjects you need to master ASAP, I think this is the best way:
Step 1) Level 5 thinking, part 1. What matters? Who cares and why? Left all gaps as variables to be found later
Step 2) Level 4 thinking, part 1: Explore the first relationships between concepts, but let all gaps open
Step 3) Search for content
Step 4) Go Level 1 to 3. You will start to filter concepts that really matters in Level 4.
Step 5) Level 4, part 2: Finish level 4 by closing all identified gaps, including new gaps you learned about during your journey in Step 4.
Step 6) Level 5, part 2: Now you are able to finish level 5, answering all questions you made in Level 5 part 1