Gradually add flour, continuing to whisk. It is important to monitor the consistency, it is not obligitory that youll need all the flour specified in the recipe. It all depends on the humidity of the flour - the drier the flour, the less of it is necessary. The dough should be pliable, not tight. Too tight dough will crumble when rolling and you will hardly manage to cover the filling. However, if it is too little flour and a lot of fat, then in the oven the dough will turn into porous mass floating in melted butter. If you have already overpoured the flour a little at this stage you can add a little ice water to the dough.