Honestly I have no idea about the liver, but IME I have better luck filling my pot almost half way with the chicken, boiling for long enough for it to actually bubble and boil, then turning it off a few mins after and letting it cool. I don't really time it, I just stand over it and eyeball it honestly. I make sure to use the broth in her food (prefers it over water) but I'm using a premix (knowbetter) so it's not as mandatory to use every last drop, plus I have a rotation including canned foods.

The thing that helped me learn to tell what's over done and what wasn't was failing a couple times and learning the color of it when it has been over vs. under cooked. Of course all my major failures ended up just going into my dishes rather than hers, but I would maybe try experimenting if you have excess liver, toss the ones you screw up/re-use them (dog treats..? fertilizer... eat them.. i eat way too much burned meat..why do I burn so much meat)

But that's just my take! Hopefully better suggestions come along. Btw, I love catinfo.org!