Wood countertops that are 3"-4" thick looks great but can cost a lot and in many cases break the budget. Using a built up edge can significantly increase the thickness of a wood countertop without taking away from the look. It saves a lot of wood and in the process saves money. There is one draw back, the labor. It takes time to add this edge so in cases where the countertop or island top is small the added cost in labor can overtake the savings in material. For larger tops the saving can be huge though and in many cases half the cost.
There are stringers that run across the bottom of the countertop so it sets flat on top of the cabinet. The built up edge does not hang over the edge of the cabinets.
