After award, the contractor submits the schedule of values for approval. Each pay application then shows the percent complete for each line.
A mechanical sub might list mobilization, underground piping, rough-in by floor, equipment, controls, testing and closeout. Each line has a dollar value.
Build it from your estimate. Use lines that are easy to measure in the field. Split material and labor if the contract asks for that.
Read Division 01 for the required format. Some owners want lines by building, by floor or by spec section.