Upgrading Builder's huts.
i would like to suggest this new idea,
my idea is that you would be able to use recources for upgrading a builder's hut to lv 2,3,4...
and with that you could then instead of having one builder on a building, you could have two for faster building.
BUT, the builder's can get tired over time, so that you can only use the second builder for 1 time in a week or so per builder's hut.
now with the way the leveling would works..every upgrade would reduce the time it took for the second builder to recover from being tired, so that you could speed up building more per week or so.
i know the last part was already an idea but i made it a little more..possible