The book actually tells you to read it 3 times ;)

The fact that I have read this book three times and don't remember this fact is a testament to the importance of this statement.

i know people that had the habit of intentionally reading it once a month while founding their startup

The Dale Carnegie Leadership course (based on this book) is worthwhile and available in many cities globally. Expensive but sometimes covered by corporate training allowance. You want the one that is extended over 8-12 weeks, one session per week. That allows time for weekly application of that week's lesson to your life, as homework assignment. The compressed (3-day version) does not give enough time to apply the principles and see real-world results. The material in the book is easy to read and very hard to apply.