If you use a needle that's too small for the thread count and the number of strands of floss, you may feel a little pop when the eye of the needle and the floss through it go through the fabric. The needle hasn't enlarged the hole enough. Although the floss will go through, the portion of it in the eye of the needle will tend to wear faster as you stitch because it is rubbing against fabric threas. You probably noticed when I wrote about types of needles, I also mentioned whether they had round or oval eyes. The shape of the eye can be an important consideration you'll want to use when you choose needles.
Oval eyes are longer and easier to thread with multiple strands of floss or thread.
If you look closely at a needle with an oval eye, you'll notice the needle diameter is fatter at the eye end to accommodate the oval eye. Other needles have round eyes, which are smaller and not so easy to thread, especially with 2 or more strands of fiber. If you look closely at a needle with a round eye, you'll notice the needle's diameter at the eye end is much the same as the diameter of the rest of the needle itself. When the needle goes through fabric, etc. It can be, depending upon the kind of stitch you're doing.