Half of my post got deleted someway! I'll try again.
Some of the "Prayer Meetings" were stopped in 1923 and then later on in 1949.
Back in those days it was called the "Prayer, Praise, and-Testimony Meetings".
In 1923 most of this was removed for field service experiences.
At one time they removed praying at the meetings altogether, because they said that the worldly people did not come to the meetings to hear prayer. The worldly people came to the meetings to hear what the Watchtower advertised.
In a letter dated November 17, 1949 reasons were given why prayer was absent from the meetings.
All of the above information comes from the Watchtower Library.
Rutherford did the same thing when he removed "singing" at the meetings. Rutherford felt singing at the meetings was worldly. But after Rutherford kicked-the-bucket, they brought singing back.
See page 3 for the letter