I agree with Carl (Moonman).
Actually, gravity does a pretty good job of holding things down. It's the side-to-side shifting and inadvertent separation of track pieces your track fasteners are guarding against. So, one screw per section should be plenty. Run the screw in to contact, then back it off 1/4-1/2 turn. You'll minimize noise transfer, keep everything together, track won't walk away over night ().
Gravity....a real downer.
KD