i find that i get this happening when i use a long thread - which i often do just because i'm lazy and find rethreading the needle tedious
but if the thread is too long there is too much wear from the eye (as you just mentioned). the weak thread is probably not very healthy for the finished quilt either as this will be the point where there is damage first... :shock:
i once read that one should never use a thread longer than an arm's length and if i follow that rule - i never have any breakage
i now generally thread a whole spool of needles onto the spool in the morning or when i have good light and/or my eyes are fresh - that way i can just use one needle after the other - with only abt. the arm's length of thread - just pulling the thread through the bunch...
works quite well