Sous vide won’t rescue a bad piece of meat. The connective tissue in your tough steaks won’t break down at the temperatures that produce a medium-rare steak, regardless of the method you use to reach them. If they’re that bad, you might want to grind them into hamburger.
My wife did this, after about 3 hours she heard a loud pop and found that our granite counters and split along a flaw! She had put the sous vide container directly on the counter instead of on a wood cutting board. Those were VERY expensive eggs…
I don’t know if that’s true, the science disagrees with you.
OK, but how long would it take to turn collagen to gelatin at 130 F, and what result would you get? Here’s a recipe for sous vide short ribs that calls for 48 hours of cooking at 131 F. That’s how long it takes for collagen to break down at those temperatures. I doubt it would take that long for even a tough steak, but it would be considerably longer than the 1 hour it takes for tender meat.
At temperatures that low, it’s enzymes that break down the collagen. Those same enzymes also work on other proteins. I suspect if you cooked a steak (even a tough one) for, say, 8 hours at 130 F, the result would be mushy and unappetizing.
I really don’t know without trying it. Like I said upthread, the joy of sous vide to me is experimenting with crappier cuts and longer baths and seeing if you can make something better than traditional methods.
I’ve done a 72 hour baby-back rib cook that was extremely well received. And, again, my 72 hour roasts were the hit of Christmas last year for the whole family.
For what it’s worth I cook all my steaks, no matter what grade or cut, for bare minimum 2 hours, usually 3-5. And to your last point, 7 hours at 130 didn’t turn my striploins to mush. They were hard and tough and awful. I suspect 12-24 hours would have rendered them far more palatable.