According to his math he is doing about 1-1.5 yards of mulch per man per hour. I can do 2-3 yards bulk myself with a wheelbarrow and close access to the truck. When working as a crew two wheelbarrow guys and me raking mulch we usually do 6-8 cubic yards/hour. If you are estimating mulch well you should never have more then 1/2 yard top leftover. That's equivilant to 6-7 bags. Just spread it over the area a little thicker. No need to bring it back to the shop. Charge the customer for what was used only.