Some upgrades are unbearable and some people dont want to gem the upgrade
What I suggest is that u should be able to boos the builder's work speed (like spell factory, barracks, mines)
It should vary by time left or so. Or it could be on set gem boost.
Like 50 gems for 2x or 3x work speed for 10 mins.
NOTE: this isnt the ability to upgrade build huts!!

