Thank you for the great responses! This is the first time I have seen this done, at any house. They usually start from one end and single pass it all the way down, from one end to the other. When the machine first started on lane 1 and 2, I was confused when it went back to lane 1. The lane man started the machine and disappeared, and didn't come back until the machine did the double pass and was already on lane 4.
Flying back ends, yes, it was flying! Had to move so much trying to find something (they lay down sport shots on old wood, so it's already tough) and when I find it, by the next time up, it's gone. But the guys on lane 3/4, 5/6, 7/8... they were killing it! My pair, I don't think anyone shot their average for the night. All we could do was laugh. it was so bad.