Hopefully this will help a little. Granted it is not Saltillo but after doing basically what you are doing for the for over a year now, for the complete 2021 release of the TRX, SHAP has never released build sheets over the weekend. Even when we have had confirmation the plant was running. In the beginning I scanned every 2 hours until I seen the pattern emerge. Build Sheets are only on weekdays and they come the morning (after 8AM Central) after the truck goes down the main assembly line. Window Stickers are in the evening (after 9PM Central) every night, also typically the day after the truck was actually finished. (Very rare instances where the truck would actually leave the factory before the window sticker was released, but those were to dealerships that were within throwing distance of the factory)
*EDIT to add* So for example, any trucks that were built on Friday would get their build sheets on Monday morning. And if the plant happened to be open on the weekend Saturday and Sunday trucks also show up on Monday so I would end up seeing rather larger spikes on Monday because of this.