Michael,
I do not have an answer for you. However, let me share some photos of a gun I recently had redone.
Here is the receiver:

Now, here is the buttplate:

You would almost say the buttplate was not done by the same person. The fact is the entire gun was done together in one container. All parts were prepared the same. There is a certain about of skill and art in the process. However, there is also an element of chance.
Besides the schedule and the quench, there are other small steps that can affect the outcome.
Pete