Hello. Judging from my own family, it made no difference.
When the war ended in 1865, they all scattered. Nothing was the same.
The idea of who was where in 1860 is actually a great place to start.
Something you need to consider is that a lot of the men did not come back.
So if they died for one reason or another, or perhaps just moved on, you know they once existed there.
If for some reason the person disappeared between 1865 and 1870, you will have a devil of a time
tracking them. That is called the voice of experience.
County lines shifted and everything else you can think of happened.