A buddy of mine out in Beaverton had the same mess a couple summers ago, his neighbor would run the sprinkler so long the water would just sheet across the lawn and soak his raised beds. He dug a small trench maybe 6 inches deep right along the fence and lined it with river rock, and it worked like a charm. Water pools in the rocks instead of his beds, and the neighbor never even noticed it was there. What is it about people who soak a lawn for 45 minutes and then act like water is a mystery? You could also try mounding up the dirt on your side so the runoff naturally flows back toward his grass.

Man, I feel for you on those two cracked blades. Water is unforgiving like that and there is no shame in losing a couple while you figure out the timing. The dusk thing might not be magic, could just be that the air is cooler and your water bucket sits at a lower temp than it would at noon. I have messed with warm water on 1084 and got a nice hard edge, but I had to move fast from the fire to the quench or she would ping on me. Losing a blade hurts, but that third one sounds like it taught you more than two years of oil ever did.