@PetrW
Zechariah chapter 13 sheds some light on all the "thirds" mentioned in Revelation...
"“In that day each of the prophets will be ashamed of his vision when he prophesies; and they will not wear an official garment of hair in order to deceive.
And he will say, ‘I am no prophet. I am a man cultivating the soil, because a man bought me when I was young.’
And if someone asks him, ‘What are these wounds between your shoulders?’ he will answer, ‘Wounds I received in the house of my friends.’”
“O sword, awake against my shepherd,
Against the man who is my companion,” declares Jehovah of armies.
“Strike the shepherd, and let the flock be scattered;
And I will turn my hand against those who are insignificant.”
“And in all the land,” declares Jehovah,
“Two parts in it will be cut off and perish;
And the third part will be left remaining in it.
And I will bring the third part through the fire;
And I will refine them as silver is refined,
And test them as gold is tested.
They will call on my name,
And I will answer them.
I will say, ‘They are my people,’
And they will say, ‘Jehovah is our God.’”
Many of the plagues/bowls/trumpets/thunders of Revelation mention fire. Jesus gave illustrations about fire as regards religious hypocrites being exposed. The New Testament talks about building with fire resistant materials as a way to survive the coming tribulation with faith intact.
Many religious people serve for prominence or money instead of for love and truth. When the religious institutions are torn down in the figurative "fire" (by means of governmental authorities stripping them) then it will be clear which "religious" people served for show and which served for real.
In Revelation, the repeated imagery of the fire, voices, thunder, etc, coming from God's throne in heaven poured down to the earth via the angels is assuring us that God's will is sure to be done and these things are rushing to a fulfillment. God has judged the religious institutions as deficient and He is making an accounting with them. The governments of the nations will be permitted to strip them completely of their stuff and for the prominent ones of all the religious institutions their "glory" will become their shame. They will be brought low. "That is where the weeping and gnashing of their teeth will be."
"The dream was given twice to Pharʹaoh because the matter has been firmly established by the true God, and the true God will soon carry it out." (Genesis 41:32)
The visions of God's judgment upon religious and secular institutions in Revelation are repeated not just twice, but many times. Their fulfillment is certain and as good as done and is hurrying to a finish.
Revelation 22:6,7,10,20
"He said to me: “These words are faithful and true; yes, Jehovah, the God who inspired the prophets, has sent his angel to show his slaves the things that must shortly take place. Look! I am coming quickly. Happy is anyone observing the words of the prophecy of this scroll.”"
"He also tells me: “Do not seal up the words of the prophecy of this scroll, for the appointed time is near."
"The one who bears witness of these things says, ‘Yes, I am coming quickly.’” “Amen! Come, Lord Jesus.”"