builder working combined

If i have 5 bilders free , n a upgrade need 10day i should have option to use more than one builder for single building upgrade, n similarly time for that should b reduced according to the number of builder working on it, if 5 builder are working on a building that needs 10 days to complete the upgrade of building it should complete the upgrade in 2 days, n if 2 builder are working it should complete it in 5 days... hope you got my idea

This idea has already been ruled out, please read stickies before posting

People want it. Let them have it.

An additional builder boosts build/upgrade speed by 5%. Cumulative, 4 extra builders boost 20%. The extra builders are committed to stay on the job until completion.