There's room for improvement in every warehouse and DC, no matter how efficient. But those opportunities may not be readily apparent, in part because people often rely too much on theory (what they think is happening) and not enough on reality (what actually is happening). Lean management tries to prevent that through the use of genchi gembutsu, a technique that involves direct observation of actual conditions.

Here's an interesting—and possibly entertaining—take on genchi gembutsu in a warehouse environment: "Be the package." In other words, walk the path an inbound or outbound order or package actually follows in your facility. "Act like you're the product," suggests Timothy Sroka, senior manager-lean operations for Menlo Worldwide Logistics. "If you're being delivered and they unload you to a staging lane, that should prompt you to ask why you're in staging when you're supposed to go directly to putaway. If somebody comes by and 'verifies' you, that's a non-value-added activity."

By walking through each step, you'll get a clearer picture of what actually happens and will be able to map out what may prove to be an unnecessarily complex and lengthy process, Sroka says. If you have to actually stand around somewhere for four hours as a package would, or you are "picked," then audited and prepped for shipping only to wait on a dock for a lengthy period, you'll quickly see all the waste that's built into your handling process, he says.