We commonly put glass worm rattles in all our soft plastics. In the winter, when it is cold, calm, and water is dirty, you can definitely tell the difference in hookup ratios for rattle vs no rattle. If we are both fishing the same plastic, same jig head, same retrieve with rattles, and on good fish, we have seen it lots. One guy has his rattle pop out of his bait without realizing it (usually due to catching a fish that pushes it out), suddenly he doesn't get bit for 5 or 6 casts, while the other guy continues to hammer fish with multiple bites per cast.
I think when the rattle matters least, is when conditions are rough enough out that there is a lot of ambient noise and the fish can't distinguish the rattle noise, so they aren't attracted to the sound then.
Class of '93 - proud Dad of a '22 grad and a '26 student!