How often carpenter needs to study while constructing what is the correct method to build to wall, and while doing that, try to find out whether the client wanted the wall or a floor, or even both of them?

Try to give any proper estimations before actually starting that kind of project, when the scope is not known and there is no buy-in to spend half of the time just to plan all little details.

It is not just "give an estimation", but a whole procedure to complete.