Thought you might like a comparison between the 72 hour beef cheeks above and the most recent 60 hour edition.
The 60 hour version, also done at the magical 54C has the texture of a mega expensive, melt in the mouth steak. It definitely requires a knife to cut it with although the knife (though definitely not a serrated steak knife). This one is served on cauliflower puree with a quick mushroom and red wine sauce.
By comparison the cheek cooked for 72 hours at the magical 54C is able to be eaten with a fork. (Photo repeated for your convenience)
You can clearly see where the fibres are starting to fall apart. At this stage the cheek could be "pulled" apart with a pair of forks if so desired.
The classic "point a finger and it magically collapses under the weight of it all" texture of an old fashioned braise would take a little longer. Possibly another 6 hour bracket. I don't really intend to push it this far as I'm quite happy with the two outcomes achieved so far. However, we all know interruptions and forgetfulness can blow cook times out beyond those intended. Who knows what will happen in the future.