I haven't looked up any of the sources brought above, so excuse me if something is being repeated here.
For the record, when RYBs talks about this subject, he says that it is a rarity that people get "sacrificed on the altar of bechira" - that is, so that bechira continues to exist for everybody, yesh neesaf blo mishpat - and they get rewarded for it. He then emphasized again that this is a rarity. I can try to dig up a recording for it but I doubt I will find it (timewise).
In addition to that, there are the people who put themselves in sakana. The middas hadin is mekatreg and someone who had deserved to die but had some application of rachmanus holding it at bay will die. Had he stayed out of the makom sakana the rachmanus would have stayed the verdict.
I once heard from Rav Brudny (in person) that there is also the middle guy, who does NOT deserve to die at all but is in a makom sakana. In that case, Hashem gives him the opportunity to earn the hatzala, but if he fails the test he will die too. (He said the same is true for anyone affected by him peripherally. For example, you have the guy who does deserve to die but his wife doesn't deserve to be an almana. If she has extra zechusim it keeps him alive for her. If she doesn't but still doesn't deserve to be an almana, she gets the opportunity to earn the zechusim. If she fails, he dies. (I wasn't sure if he meant this is because the failure of the nisayon makes her now deserve it or if it's just that she doesn't have the zechusim.) He referenced the Ohr Hachaim on Devarim 1:39 for an example of this phenomenon - Moshe didn't deserve to not go into EY but failed the nisayon that would have enabled him to do so, ayen shom.
Sorry I don't have any mekoros for you to look up. Just putting this out there for anyone interested.