The Yonex representative in Portugal said that shouldn't be added additional tension for the knots, because if the shuttlecock hits that area, the string could broken. He also said the in the Madrid world championship, the stringers didn't add additional tension for the knots. I would like to know which are your comments. Thank you.
You will be surprised that tournament stringers are not the best of stringers. I have seen and examined racquets belonging to top ranked players and frankly I am not impressed. The patterns were wrong, the racquets have micro cracks at the 3 and 9 o'clock in many racquets, and the knots look as if they would come out of the grommet.
You get less tension lost when tying the knots and the clamps are released. For your reference: http://www.badmintoncentral.com/forums/showthread.php?t=38908