any thread can become --- not usable----age is not always the reason- i've had brand new thread that was weak- not usable- i've had 20 year old thread that was still strong and just fine---there are lots of reasons for your thread to be no longer (good) storage, humidity, or lack of, temperature, manufacturing process....
it's generally a good idea to do a little *tug-test* on every spool of thread before using- regardless of what fiber it is...just to save yourself the aggravation of threading your machine to find the thread breaks every inch...