From 'Collaborators of the Conspiracy", a 1992 article in
The Third Decade by Mr. William Weston:
Mr. Weston suggests that the crew moved up from five to six (on Wed 11/20) even though the fifth-floor job was not fully completed. From this he suggests that the floor-laying crew of Depository men (Messrs. Shelley, Givens, Lovelady, Arce, Williams) may have been knowingly securing the sixth floor in good time for Friday's motorcade.
However, we can now see---------thanks to Mr. Harold Norman's information about an external flooring crew-----------that no such foreknowledge would have been required on the part of the Depository workers, nor for them to have made the call to move prematurely from five to six. They were simply following instructions, and helping out the outside crew in good faith. Once the assassination happened, they were horrified (and terrified) to realise what those men had really been there for----------and why the move up to to six had to have happened when it did.