It is great that we don’t need a free builder to re-arm traps and other defenses.
We shouldn’t need to have a free builder available to do anything that requires 0 minutes.
This is what we do now: We cancel an upgrade in progress, spend all our gold upgrading walls, and then start the initial upgrade from the beginning. There must be a better way.
You may be thinking “but you couldn’t build without a builder, silly!” Here is a scenario for you:
A hard-working builder, Bob, has been upgrading a gold mine for 3 days solid with 2 days left. He hears the alarm bells dinging from across the village. They need better walls to protect against advancing enemy giants. He welcomes the 0 minute break from the monotony and fixes up the walls. Exactly 0 minutes later, he is back in the mines finishing the upgrade. The guys down in the mine, working 16 hour days without holidays or weekends and risking Black Lung Disease, don’t even notice Bob missing. All is well in the world.