Builder Idea

Add a button to buildings being constructed/upgraded that you can add more builders to it. For example, if you have 2 free builders, upgrade a elixir collector which takes 1 day (24 hours), and add your second builder, the construction/upgrade will only take half the time (12 hours). Obviously, the second builder will not be free when used.
Adding a third builder divides the upgrade time by 3 (8 hours), and adding a fourth builder divides time by 4 (6 hours).
Feedback please!

Super cell has already ruled this idea out