Schedule two 4-hour learning sessions daily, with every 4 hours as one unit of study.

This is not about learning while taking breaks within those 4 hours, but rather 4 hours of continuous, focused, and efficient learning.
The 4-hour learning method makes it easier for you to enter a flow state.
When you sit down and start thinking, the hardest part is already done—that is, overcoming the emotional threshold of entering a learning state.