Just trying to get some ideas. My dad has become a habitual spoke breaker. He has had his rear wheel replaced 3 times and has broken probably 6-10 spokes total.
The wheel has been tested, trued, tensioned etc.
He rides a comfort bike (2005 Jamis Aragon) and is not a small guy, about 250-260lbs. He has lost over 100 riding though
The bike shop was telling him it is due to torque because he cross chains too much. He spends almost all of his time in the big chainring, even down to the biggest cog and can mash the pedals pretty hard. So the LBS was saying that when he is crosschained like that and pedalling hard he is causing too much lateral torque on the hub which is causing spokes to break.
Does that sound like a feasible answer? His wheels seem sturdy enough (36 spoke count). And I know he is getting frustrated by this problem.