You will use them many many times. You cannot have too many. Go in a logical order that makes sense to you and get walls, ceilings, floors, everything. Cover wiring, ducts, water lines, gas lines, sewer lines, light switches, and plugs. Pre wre some ethernet if you can, it's invaluable. Just take it to cable boxes or phone line boxes if nothing else. Run ducts from a few spots to the attic is handy also in case you might do ethernet or similar later.