I have found that when you place several screws in a small area and the squeak won't to away, it's because there is a nail that just missed the joist but is rubbing it when you step on it. Simply pry it away from the joist and you're good. On the other hand if the ceiling is closed, live with it.
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.
The problem with all of this is when you have carpet covering your squeaky subfloor. In that case its not practical to just start driving screws thru the carpet unless you want to ruin the carpet. I have that problem in my home. Several areas with squeaky floors possible from old nails rubbing the OSB sheathing. I cant tell because the carpet is laid over it and Im not removing it. Cant get to it from below either because its completely finished.
i worked for a builder in my younger days and we were in the framing stage and there was a squeak in the floor. I told him every house should have one squeak, he agreed and told me to fix that one. turned out to be metal bridging rubbing
The older I get the better I was