I'm not disagreeing with you. But you were disagreeing with
@Hammster, whom I think you misunderstood. I have little doubt he asks God for mercy too, probably every day; but his point is —if I may paraphrase and lighten the point— that we have already had more mercy than we deserve, and, particularly, that we [redeemed] have all the mercy we need for salvation. That particular mercy is already in play—no need for the redeemed to ask.
When, by my own measure of my deeds and attitudes, I find myself more closely resembling the lost than the saved —yes, I cry out to God for mercy. But that cry is for steadfast obedience and faithfulness and fellowship —not for salvation.