In principle, it is best to start Lean Manufacturing improvements as close as possible to the customer. That would mean taking the "next process is your customer" approach to all activities. This is called vertical development of Lean Manufacturing improvements - lateral improvements are when they are moved to other products.

Many think of leveling as leveling out two factors - capacity and load. For Lean Manufacturing improvement, leveling means thoroughly leveling out product types and volumes in accordance with customer needs. Begin by breaking down the production output into small (usually daily units). Then compare the daily volume of product with the operating hours and calculate how many minutes it should take to turn out each product unit. This unit production is "cycle time". Then figure how many people are needed and what the capacity is.