I work for a defense contractor in Los Angeles and that's exactly what's happened in our industry. I'm not sure which company was first, but nearly all the defense corporations here are on the 9/80 schedule where you work 9 hours/day (80 hours for the 2-week pay period) and get every-other Friday off.
I worked at Lowe's one summer 18 years ago when I was on summer break during college. From what I can tell, little has changed, so I have some insight here. The schedule for workers constantly changes; very often, people that worked there would call in sick or just not come in. The managers move you to where they need you. I was hired strictly as a cashier, but I would often be moved from Tool World to the outdoor section to the main cash registers - all during one shift. Each of these areas has a very different customer type. Being a young college kid who never owned my own place, I didn't know much about any particular area. I tried to be as helpful as possible though. Some customers understood this; others were just plain rude.
Funny story: Management often put me on the cash register guarding the entrance/exit to Tool World because I was very thorough in checking customers as they exited; there was a big problem back then with customers stealing small high-value tools by putting them inside other, less-expensive products. So, it was my job to prevent that. Anyways, I didn't know much about tools, but there was a girl about my age who was very knowledgeable in that area. She was the Tool World expert who roamed around the section. One day, a contractor came up to me at the cash register and asked me some very specific tool-related questions. I had no idea; I said, "I'll call the expert in to help." He said okay and waited. When he saw this young girl with glasses walk up, he looked at me and said, "you've got to be kidding me?"...then he walked away and left! Funny thing is that she probably could have helped him!