November 25th, 1968 (8L25) was a Monday. But yes, to answer your question, it wasn't unusual to work on weekends, depending on the requirements of the parts or the cars. Major holidays, no. Valentines day - yes. I'm not sure exactly what holidays they got off, but John Hinkley (JohnZ) would know. maybe he'll report in.
By the way, they skipped the letter "I" on items that were stamped, like Distributors, Alternators, Starters, etc...
Ed