They are still teaching it! Destruction of 1/3 of the earth is equaled to the convention of 22,000 plus proclamation nobody in the world even noticed.
Watchtower 2009, 1/15 pg 32:
8:6-12; 9:1, 13; 11:15—When did the seven angels prepare to blow their trumpets, and when and how were the trumpet blasts sounded? Preparation to blow the seven trumpets included giving direction to the revitalized members of the John class on earth from 1919 to 1922. Such anointed ones were then getting busy in reorganizing the public ministry and building up publishing facilities. (Rev. 12:13, 14) The sounding of the trumpets represents fearless proclamations of Jehovah’s judgments against Satan’s world by God’s people in cooperation with the angels. Notably, this began with the Cedar Point, Ohio, convention in 1922 and lasts all the way down to the great tribulation.