The recipes for bone broth that I have followed have always called for some veg quite late in the process.
The bones go into the slow cooker, covered in water with about a tablespoon of cider vinegar then ticks over on low heat for 48 hours. The carrot, onion and celery, go in for the last 12 hours. Any longer and they give a burnt bitter taste to the final product.
I always see the difference between broth and stock being the time it is simmering. Stock for a few hours, broth for a couple of days. The addition of the vinegar helps break down the collagen in the gristle etc that clings to the bones. That is what makes it good for IBD patients as it helps to heal the gut.
I follow a recipe (sort of) from the Katz fellow and various IBD sites and recipe books.
I don’t drink it unless it is really fresh, but pot it up in 500ml pots, freeze and use in recipes that call for stock or water. The broth turns into jelly and is very very rich. Goes great in my curries. In this day and age a lot of people are averse to bones in their food, so using bone broth like this offers the best of both worlds, no bones on the plate but the broth delivers the flavour and goodness.
Edit: This similar to the bone broth recipe that I use. Given that I have made it a lot of times over several years I don’t actually follow a recipe line by line anymore. It is now a bit instinctive.
https://www.farmersalmanac.com/10-benefits-bone-broth-25512#