You recommended the Simha Kriya breathing exercise released by Sadhguru a while back because it's good to raise ones Gong and it takes only a couple of minutes to do. But after practicing it for a while a bunch of questions came up which I hope you can help me clear up. 
1. I found that some people do this exercise with the eyes open and rolled up as if they are looking at their third eye while Sadhguru just did it with the eyes closed. How should you do it? Some website claimed that the tongue rolled out is an imitation of Kali who is supposed to be the goddess of energy and power, so that would make sense but I'm unsure about the eyes.
2. As I remember you said to do it only once a day but Sadhguru recommends it 2-3 times a day as long as there is a 4 hour break between the sessions. I did it only once per day so far as you said  but I tought about doing it at least two times, once after waking up and once in the afternoon. How often exactly can you do it?
3. After you did the 21 breaths with your tongue out and 21 breaths with your tongue rolled back, do you inhale the 22nd breath (which you hold for one minute) through your nose or your mouth? Again I've seen multiple versions of this, Sadghuru did it through the nose but others claim you must do it also through the mouth. One video even said you should already hold the 21st breath of the set while Sadghuru seems to hold the 22nd after he finished the 21 normally. What's your take?

From what I did so far... I don't know if my Gong already increased from it but I feel that this exercise might become addicting.