Landing lights saved mid-air between RAAF Caribou and a USN Crusader in 1965 while en-route at 100ft AGL in really rotten weather. We each saw the other's lights and turned right just in time. Operational pressure had our Caribou there but I could never figure why any other aircraft would need to be right there. Nevertheless, that particular risk was considered greater than indicating our position more acurately to enemy ground forces.
In nearly 40 years of flying I believe this is the only case where landing lights on saved my life. I figure just making it safer is worthwhile, so I'm so far ahead on the deal.
Every pilot should not have to learn by experience. Unless your company has some other procedure for lights, landing lights on below 10,000 ft is a no-brainer.