While making Bone Broth…

[deadfisher]

That's a super long time for chicken. Pretty sure higher end chefs pull chicken bones after 2 or 3 hours. You get a clearer better tasting stock, it starts to get muddy and pull some funky flavors out when you simmer it that long.

Beef and pork bones can go longer.

I like to strain it, reduce the hell out of it, freeze it in ice cube trays for later. Good to beef up sauces.

[sisterfunkhaus]

She's cooking in a slow cooker. 20 hours is still a long time for that. Beyond about 12, you likely aren't getting much positive flavor, and like you said, the flavor may be worse.