That would be a little excessive for February which just happened to end on a friday in 69, but not out of the possibility if the actual calendar month ended on a tuesday or wednesday.
GM gave Fisher the orders for the cars to be built in advance so fisher could plan their work. Did they give it to them a days production (912 cars) a week ahead, or 2 weeks I don't think anyone here knows that. Fisher would take those orders, which in 69 had an order number that became the body number for each car, but in 67 and 68 Fisher assigned a sequentially assigned number to each order (which became the body number) so they could track the body. Fisher then assigned a build week that the car was to be built in, which was generally in the same order they were received) Say the order for 1 days worth of cars was delivered to Fisher on Feb 28th and they were going to be built 1 week from that time. The trim tags were prepared with either a sequential number (67/68) for each car or the order number as the body number and whatever other option and color info needed for the order. At this point this group of tags was set aside and the next 912 tags were prepared, and ultimatelyt there should have been 5 groups of 912 cars in a single build week. As the time arrived to build the cars the scheduler at Fisher would go thru a days production worth of 912 tags and regroup them based on Fishers build restraints. He had to look at things like convertibles, vinyl tops, possible RS equipment and anything that would take extra time on the assembly line. You certainly wouldn't want to see 2 convertibles right after each other, as it took extra time to install a convertible top, same with vinyl tops. If I had to guess you would never see 2 convertible closer than 8 or 10 bodys apart, maybe a little less for a vinyl top car. I have not seen any data to indicate that there was any grouping based on color. ie he did not go thru the order to find all of the red cars and put them together. So the scheduler takes his 912 sequential order body numbers and shufflles them up to meet whatever construction constraints Fisher had, so maybe the car with body number 001 gets shuffled so it follows car 027, and car 030 gets brought up to the front of the line, also if GM decided they need a particular car to be built earlier than any others they could request Fisher move it up (or back). At this point the scheduler assigns the work order number to the car (this is the W/O number on the LOS tags) that indicates the position of the body in that days assembly order, (ie body 1 thru 912) and releases it to the plant for building. (theres a bunch more stuff that happens in the background like ensuring the parts for these cars are on hand, you have adequate paint to paint the bodies, interior components of the correct colors and styles are on hand, etc. On the day of assembly those tags are delivered to the floor and the bodies are built in the order specified. It took about a day to a day and 1/2 for a body tub to go thru Fishers side of the plant. Once the completed rear half of the bodies were completed by Fisher and sent over to GM in whatever order they started out in they were given a sequential VIN. first car got the first VIN then each one incremented up by one. GM had a body bank of 6 lines that held about 72 cars total that allowed them to reorder the cars based on their build contraints things like RS, consoles, SS's and Z28's (due to stripeing requirments) that took extra time would be divided out and then metered back into the single common assembly line so that the line would not be overloaded by having multiple highly optioned cars arriving at an assembly point one after the other. This configuration of the line means that the cars did not progress down the GM side of the plant in purely increasing sequential order. They were almost in order but the higher optioned cars, console cars, RS/SS's probably trailed by a few VINs, maybe 6 to 8 depending as they were fed back into the assembly line. The only point in time that the cars were purely in increasing sequential order was when they came thru from Fisher and before they got to the Scheduling bank. It took about a day for the car to go from the scheduling bank to being driven out the back door and getting delivered to the shipper that was going to deliver it to the dealer. So you can see that there is a delay from the reported last VIN of the month and the end of the actual build week stamped on the tag, that could probably be as much as 4500 cars, depending on what day of the week the month actually ended on.