I have not used ductape for splits, we normaly have paint and nails. We do try to put down ductape start and finish lines the night before.
We are in Florida, the race starts just after sunrise so we are putting out mile marks and clocks in the dark. To find the marks in the dark we prep the day before by bang in wooden stakes at each split point. The posts are pre-painted with very bright marking paint. That way we can find them in the dark on race day. They show up fine in my cars headlights.