Certainly the advice to put the game on half speed to lengthen the life of the older builder is sound. I'm not convinced that the exercise stew is worthwhile. It is much easier simply to set your builder on fixing the huts. Make sure the builder is "fixing" the hut, though.

I assume from the wording of your post that you have no building projects underway at the moment. If you have any still to start you might consider advancing them as villagers tend to wander away from fixing the huts, whereas they stick to their task much better if engaged in a proper building undertaking.