Has he gotten to the point where he will work on his own without you having to put him back to work? I've got a guy (fortunatly 5th gen) who will work one cycle, then wants to go off to do something else. It took quite a while (and a few red gloves!) to get him to self-start working.
Arnie seems to have a good system: 3 work cycles, then a break, then back to work.
And yes, leaving the game on all night really does help!
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If I can get them to think, I'm half way there...