I think it would be useful if hearthlings would mine different segments. If you have 10 different mining projects and 10 hearthlings, one hearthling should go to each, not 4 to one and 2 to another and so on. It would make more sense for one hearthling at each unless they were able to have multiple hearthlings at 1 mining spot, like 5 spots but 10 hearthlings, so 2 per.
mining as a hole needs a rework.
currently its more a hassle then anything. and its required for later game builds. out side of making a strip mine actual tunnel mining seems like a waste of time, especially do to building limits.
Would post a rework idea, but I have already posted one somewhere. I think.