To Teach is to Learn
Mentoring, tutoring, teaching, peer studying, whatever you may call it, the act of giving someone else information in an understandable fashion will make you learn, even if you know the material already.
Recently, a friend of mine came to me and asked for help on an Economics quiz. I spent an hour explaining price elasticity in Mandarin. Sometimes, he didn’t get it and I had to make up wacky examples on the spot to illustrate concepts. I tried to relate the cold and abstract theory in the textbook to current life, explaining price sensibilities with specific real-world items and situations. If you usually buy grapes at your local supermarket for $1.99 a pound, and they suddenly increase their price to $2.99, you are likely to shrug it off. However, if you come back the next week and the grapes are still $2.99, you will strongly consider buying your grapes elsewhere. This is how I explained the concept that elasticity increases with time. Most importantly, time passed quickly, meaning that we were actually enjoying ourselves studying. Neither him nor I would have studied that diligently without each other. He obtained a score much higher than his average in the class and I scored a 100.
What I’m trying to convey through this example is that you can achieve much more by teaching someone or merely studying with someone else than your textbook. You can clarify and consolidate your knowledge, improve your explaining skills, your verbal organization and presentation skills, expand your social network and reputation and most importantly help someone else achieve their goals. Yes, you can accomplish this much by studying for a test.
In study sessions, I find groups of two to be most efficient, simply because any more members and you risk being distracted by banter and procrastination. I don’t suggest studying with your best friend for this reason. You will engage in gossip and conversation rather than studying seriously.
Don’t hesitate to emerge from your cocoon of social awkwardness: share and accept knowledge from your peers. Sign up to tutor. It will help both of you get ahead in life.
Dk's Ordinary Life 
Only wanna admit that this is very beneficial , Thanks for taking your time to write this.
I’m glad that you enjoy my website. I also write for myself, to record ideas, values and information I want to remember for later. You can imagine that strangers approving of these ideas gives me a boost!