The Book of Revelation repeats many things from earlier in The Bible.

This is well known, people have written much on how it's judgments echo the Plagues inflicted upon Egypt before The Exodus.  And other repeats are noted too.

So why do these "Revelation obviously isn't Chronological" people have so much trouble accepting that some of these things will happen more then once over the course of the Time of Jacob's Trouble? 

Remember during the Wandering God inflicted Plagues upon Israel in their disobedience.

Jesus refereed to Earthquakes, plural, in the End Times in Matthew 24.  Revelation always seems to refer to a single Earthquake at a time, but does so five times.  But Post-Tribbers seems to think they are all different accounts of the same Earthquake.  So when does Jesus' plural Earthquakes happen?

Trumpets Biblically are Warnings, there are some compelling reasons to see each Trumpet as a warning of each Bowl, but there are also flaws with that.  But the point here is the parallels that exist are all the Trumpets being lesser.  A Third of the water turns to Blood in the Trumpets, all of it does in the Bowls, same with the Darkening of the Sun and Moon.  Those can't both be true at the same time.

And the Moon turning to Blood is NOT the same thing as it being darkened or not giving her light.  The shade of Red that Blood is is actually a very bright shade.  I don't think this is a Lunar eclipse, it may or may not have some natural process involved.  But Dark means it is not currently giving or reflecting any light.  Meaning the only color it could be is black, which is actually the absence of color.

Now I've seen Post-Tribbers assert "how can a Star fall in the one Trumpet in Revelation 8, and a third be Darkened in another, and then a third fall from Heaven in Revelation 12, if they all fell to the Earth in in the Sixth Seal in Revelation 6?".

This was not asked by a Flat Earther, but it directly relates to how Flat Earthers abuse the concept of "literal" interpretation when it comes to things like the Stars.  And I already did a post on dealing with what The Bible says about Stars.  "Star" to the Ancients didn't mean the modern Scientific definition.  Revelation 6 is poetically describing a Meteor Shower, Revelation 12 could be another Meteor Shower.  And Wormwood is a Comet.  None of this contradicts a Chronological interpretation of Revelation.