OK -- a question. I admit I am not the best cook to begin with.
When I have made beef stew the beef comes out tough and not tender and it doesn't pull apart like I would like it. I buy the precut stew beef and lightly brown it b4 putting it in the crockpot. Maybe I am cooking it too long before???
A tip I learned from Tyler Florence on the Food Channel is that it is the slow heat AT THE END that makes it fall off the bone. As you are cooking, for a while, the muscle fibers contract & seize up & become tough. This happens especially if cooking too fast with high heat and no liquid.
People make the mistake of cooking at the end, with too high heat, not long enough, and no moisture. You need all
three components. Continue cooking slowly at a low heat beyond that point of toughness in a liquid or sauce, and the muscle fiber breaks down, until it finally falls apart & off the bone.
So if ribs or any meat is still too tough, keep cooking! If your heat is low enough and you have enough moisture, you can almost never OVER-cook meat.
That's why the concept of a crockpot works, no matter what time someone comes back to dish it out: in 6 hours or 10 hours later. Once it's
past the falling apart stage and is still cooking on low heat in liquid, it will be fine.
And while most of the recommendations on the DIS use a crockpot, I still cook the old fashion way over the stove, in a very high sided pot with a lid. I don't get to leave home, as I do have to monitor it. But it works fine. And I've never cooked anything for 6+ hours that way. On the stove, it's been maybe 2+ hours, simmering, tops.