Note that the work content for each station is not precisely balanced: work is not divided equally among the operators because the work elements cannot be “sliced and diced” to achieve the perfect balance. No two work elements are ever exactly the same, and elements cannot be grouped in a way to make work content at each station exactly the same. And if a product is new to the assembly line or has a short run (is produced infrequently), the variation can be even greater as operators get used to what they are doing. Many factors further negatively a‚ect balance and productivity. Let us take a look at some of the most common factors.