Now I am going to sound really dumb, and I am asking a really dumb question, but why is this such a big deal? I have sewed garments for many many years, and except for the right size needle for the fabric I am using, I've never given much thought to thread size/type versus needle size, or how long the needle has been used. I usually use a needle until it breaks. Maybe I've just been lucky, but it has never seemed to be a problem for me. Explanation, please.