Instead of there being a never-ending supply of wood for the fire, could the builders not have to cut down trees, and chop the wood to keep the fire going..one tree can give them a lot of firewood..so they get good points for cutting the tree down without dropping it on the rest of the villagers...and a few points each time they chop up xx many pieces from the tree?....this way still increasing their builder skills after all the buildings are finished.

Perhaps only builders can build small rafts or boats to go further out in the ocean so that only master farmers are allowed to fish for fancier/better/bigger fish. It could mean, trainee builders may build something that will either fall apart..or leak...therefor not make the fishing expedition a success..but gain a few points towards adept skill.....adept builders build better ones....and therefore gain more points with each one built leading towards master skill?

If scientist research a need for a tool..( ie spears/bows for hunters...or some sort of gardening/fishing tools for farmers)...then its up to a master builder to create it?