What it is
Laying on is the opposite of fishing on the drop. You set the float overdepth so the bait stays put on the silt or the shelf, and you wait. It is how you present corn to tench, punch to a better roach, or a worm to a perch that will not chase.
The float may sit at an angle. That is fine. A lift or a slide is the bite. Dragging is the enemy — backshot, a heavier float, or less line on the water.