Usually because when it reports KBs in bad sectors the damage has already started.
It will repair and move what files it can to undamaged blocks, but depending upon how many KBs it finds, deterioration can be quite quick from there on in.
If it just finds a few KBs then at least you are forewarned and can create a system image onto external media in preparation for its replacement when it finally goes.
On my Toshiba laptops there is a Toshiba HDD/SSD alert that will pop up but I don't know at what stage that would be.
I have the 30 day free trial of HDSentinel stored in my downloads folder which I'll run now and again and that will give you a written report.
I uninstall it straight after using it to stop the clock on the free trial and then run it again as and when, but I believe the Pro version monitors the HDD/SSD although I don't know at what stage it would start to alert.
Hit the green download button and then select the first free trial .zip. -
https://www.hdsentinel.com/