fromageGB, on 2018-December-11, 06:03, said:
I certainly would NOT suggest a 20/21 2NT open, but thoroughly agree with those who say it should be no more than a 2-point range. How can responder unilaterally make the game decision opposite anything wider? I too used Kokish before I adopted transfer responses to 1♣, but suit bidding is better after 2♣ without Kokish getting in the way.
Out NT ranges are 12-14 starting 1♣, 15/16 opens 1NT, 17/18 starts 1♣, 19/20 starts 1♣ but has a different sequence to a 2NT rebid, 21/22 is 2NT, 23+ starts 2♣. I am more than happy with this choice.
I would suggest a 20/21 2NT opening to those employing a 15-17 1NT opening, which is probably a majority of all bridge players. I wouldn't be surprised if 14-16 and 19/20 become widespread in the next decades though, as they are more aggressive and allow a greater percentage of hands to be played systems on.