Accurate explanation of Turnblocking

I would like some clarity on the turnblocking system. Is it pure chance? Is there an actual formula? Twice in 1 game my gen stack of 20+ was TB by 1 unit when my move was first move. I have read previous explanations of TB but I dont know if they are updated or accurate. Part of me feel like it might just be pure chance( this is emotive, due to being TB twice by 1 unit and capped after making it first move). Would love the objective minds to shed light.

https://atwar-game.com/forum/topic.php?topic_id=16145

There is an old thread by Laochra on this topic, but Clovis pointed out inaccuracies/doubts. In addition, most of the insights were based on empirical tests rather than definite knowledge of the implementation.
So for the moment turnblocking still is mostly an art based on experience, but I strongly agree that more tests should be made, respectively Dave should weigh in to clarify the actual mechanics.