The problem with the 3 thing rule, is that as they age, "things" change. What was important to them or made them happy a year ago is not necessarily the same today.
I think it's important to look and try & be objective: is pain controlled? are they happy?
I remember watching Heart take a dump and she fell into it. I was horrified, ran to get a wash rag and a towel, and she & I were running towards the door at the same time: me from the inside and she on the outside She was happy as could be, grinning from ear to ear I washed her up, made no fuss and she was no worse for wear. It happened a few times.....she hated to be supported, so I let her be when I could.