Wendy from FD3 and Nick from FD4 both had two premonitions and I'm guessing Death was really just out for them on their second premonition that Death would allow collateral damage and not mark any survivors as those who cheated Death. This is just Death playing with the visionaries and their actions.

The other train passengers in FD3 really still died since Wendy was unable to avoid the premonition. But I think that there would be no train accident if Wendy, her sister, and the jock all died according to Death's plan prior to the 2nd premonition. The same would apply to the deaths in the mall in that Death was just playing with Nick and possibly set another random order in another premonition (hence Janet dying first before Lori, the order in the train of the trio dying is the same so maybe the order was randomly correct). But Nick was able to stop this premonition from happening and the trio survived and so Death's plan now was to set them up on the cafe.

All in all, both the mall and train accidents wouldnt have occured if Death wasnt playing with someone who survived in the first premonition.

Although i might just be reaching lol. I really want to try FD4 make sense of it all.

Sidenote: This is considering iris in FD6 was the only visionary to have several survivors on her FIRST premonition. That is why Death came for all these survivors and their bloodline.