Stable will update the following week on Wednesday, not two days later on Friday.
Also, that is all dependent on bugs in that Open Beta build. December 19th 2018 update had issues, was then update the second week of January, the 16th (mind you the long break was due to the holiday) and there were still issues. To two weeks later on Wednesday Jan 30th. was another update. That update fixed the issues. The following week, Stable was update to that OB branch.
So when the Tomcat drops, they will make sure there are no bugs. If there are, they will Hot fix on Friday, two days later. If that is all good, then the following Wednesdays Stable will get the Hot fixed OB update.