It might go something like this: A salesperson looks at the job, determines the best system for the customer and gets his or her approval on the contract. Then another person gathers the necessary materials and explains the job to the installation crew. The crew installs the system and someone collects. Finally, someone else follows up with the customer.
There is a procedure to accomplish this. The better your procedure, the more efficient you are and the more profit you make. You don't install a system without a plan, even if it is just in your head. If you do, you run the risk of putting in the wrong equipment, not doing what you promised the customer, needing to run to the supply house to pick up forgotten parts or performing a poor installation that takes longer than the budgeted hours.