The Answer could be: The WTC Buildings were completely closed off to everyone on the Labor Day weekend for 3 days prior to 9-11 for maintenance, according to the information I have gathered so far it has been suggested that the only people allowed in the buildings were "maintenance staff and technicians or persons authorized by WTC Security only"
EVer worked for a big company or factory? Anyone who has knows the weekend overtime is always an ongoing planning. Thurs/Friday everyone is scrambling for it, and the diehard overtime addicts, are always on top of it. Even non-union places have overtime books, but in union shops everybody is in overtime groups according to your classification. Everyweek your overtime hours are logged, and books are maintained religiously.
There are more grieviences filed over overtime displament in union shops than any other grievience. Especially Maintinance crews, they always plan upgrades or major things around many holidays of long weekends, where the holiday Day pays triple time. These things are planned months in advance, require ordering of materials, meetings, and more meetings. The WTC probably had 3 shifts 24/7, as factorys and big buildings can never be unmanned, always having electicians for sure, and probably pumbers. Many things in Maintinance, require people, and are never left completly shut down.
Your theory proposes, that all these maintinance people would be home, and some sort of false security and maintinace crews would somehow end up in control of the buildings, plus management personal--2 of them. The overtime book, would have the lowest overtime logged people all asking, "I'm low man in overtime, we never are unmanned, how can you not bring me in? You would have mass grievences for overtime immediatly. Not only is the idea you would have not have thousands of employees in maintinance trades, all looking at these overtime records, management would have been in meetings and planning for some big project for months ahead, that was going to require some "special long weekend", and special crews, and special security.
Looking a little deeper into this,
something about the theory didn;t quite add up. The WTC was attacked on Tuesday, Sept. 11, 2001. LABOR DAY IN 2001 WAS ON THE PRECEEDING MONDAY, SEPT 3 RD. According to your plan, terrorists decided to wait until the following weekend was past, 8 days
after the 3-Day weekend explosives planting? They would not have needed the airplanes, they would have blown the building the minute they could have.