All of the seven churches described in the Revelation to John were within a few hundred miles of each other. John wrote this last book while he was on the island of Patmos, about 40 miles off the coast of modern Turkey.
One common interpretation of the seven churches identified in the Revelation to John is that they represent seven separate church eras starting with the first century church and then ending with the seventh and final church era just before He returns.
The problem with this interpretation is that there is nothing within the text itself that suggests that we should do that.
Secondly, these seven churches are never enumerated like the other sequential events listed in the book - like the seals, trumpets, or bowls. Eg. 1st seal, 2nd seal, 3rd seal...
The sequence appears irrelevant. Rather, it's the content written and directed to seven specific churches in Asia Minor that is important.
To the seven churches in the province of Asia.
Rev 1:4
On the Lord’s day I was in the Spirit, and I heard behind me a loud voice like a trumpet, saying, “Write on a scroll what you see and send it to the seven churches: to Ephesus, Smyrna, Pergamum, Thyatira, Sardis, Philadelphia, and Laodicea.”
Rev 1:10-11
To the angel of the church in Ephesus write...
Rev2:1
While the content of each letter is directed towards a specific church, all seven churches received this admonition at the end of each letter - "He who has an ear, let him hear what the Spirit says to the churches."
So, while the instruction was specific to a church, it was also to be considered by all.
Even though some of the details described can be linked to specific historical events (martyrdom of Antipas) or places (throne of Satan - Pergamon Altar) within that particular church, the instruction was intended to be applicable right to the end of this age and not just for a particular moment in history.
But if you do not repent, I will come to you and remove your lampstand from its place. (Ephesus)
Rev 2:5
Nevertheless, hold fast to what you have until I come. And to the one who overcomes and continues in My work until the end, I will give authority over the nations. (Thyatira)
Rev 2:25-26
Remember, then, what you have received and heard. Keep it and repent. If you do not wake up, I will come like a thief, and you will not know the hour when I will come upon you. (Sardis)
Rev 3:3