Not everyone agrees, admits Mike Roumaya of Business Solutions International LLC. But in his company’s studies using value-stream mapping techniques, manufacturing plants operating a third shift often see a volume gain equal to only two to four hours of additional production, not the whole eight.

“Simply put, production is not linear when a third shift is added,” he tells attendees here on Monday. “There’s not as much support staff. You often have to call somebody at home when you need something. Uptime can drop to 15% to 20% with a third shift.”