I did a commission a few weeks back and things didn't worked as planned.
I had to end it but managed to find an arrangement with the client.

I was to continue working on a map started by another artist.
Yet, I've found myself having to work on what the previous artist had not completed.
At first I though that it would be some simple modifications...

Soon it was clear to me that the client did not know what he wanted his world to look like (and where to place the elements like mountains).
This was more like worldbuilding than mapmaking.
I've built my own world too and I know it can take a lot of time and a lot of back and forth.
It's fine when it's your world but not so much when it's someone else world.

I was either expecting that:
I was to follow a strict guideline.
I was given a lot of freedom to fill the gaps.

But found myself with little freedom and no clear instructions.
I also had no idea of how many changes would come after.



I want to know if this kind of situation is common and how others are managing it.

My 2 solutions would be:

1- Refuse the offer. If you realize that the client doesn't know where he is going with the project : tell him to take more time to flesh out his world.
That's eventually what I did.
2- Charge more if you need to go through the process of building the world and the client is picky.