With the introduction of the new Quest System, the old boundaries of the Quest System have become obsolete. As soon as you build a building, you will get resources back when finishing it. As an example, here's a calculation:
For example, if you build an HQ level 20; reward value set to 10% → upgrade costs for the HQ (wood) 7.266; 10% of that value 727 → this is greater than 100 (predefined amount) → you receive 727 wood instead of 100 wood. Special case: if you add more than 5 buildings to the queue the costs will increase, but the reward will be capped at the initial resource costs.