More of an adjective to describe a noun. The example that comes to mind is the umbilical cord feeds and natures but once birth happens doctors sever it. If left too long it could harm the baby. So another way to look at it is something is good but too much of it will be bad. A phrase that comes to mind is a quote from The Dark Knight:
"You either die a hero or you live long enough to see yourself become the villain."
I write poetry and like to include repetitiveness in the sense of words and their definitions if that makes any sense. I am still in the editing part of my poem but here is the part where I would like to insert such word if it exists.
Stop writing encores that sound like the first one, you're just rearranging the words
Give birth to new comings and with them comes what once feed you with essentials
So sever all those ___ umbilical cords
So the word would go in the last line between "those" and "umbilical".
Best Answer
Obsolete may be effective in your context- not exactly the meaning described but goes with umbilical cord well.