I've made bone broth in a big pot with a lid and in the crock pot. I've never let it simmer anywhere near that length of time. If you wanted to do so, I would assume that you would need to simmer it on very low heat with the lid on and/or add water over time to replace what is lost. It would not be wise to let it simmer on the stove overnight though - a fire waiting to happen.

I've read on multiple websites and have heard from some other MFP members that you should roast your bones in the oven before making the broth. It helps the bones to leach out the collagen and other nutrients more readily into the broth and thus, increases its nutritional value.

I've heard about adding apple cider vinegar but I've never tried it. I like roasting the bones, it adds some additional flavor as well as nutrients.