I do not know if that is true, I've closed in on 100 kills but I don't recall actually getting to 100 kills. But one thing that has happened (for me at least):
All of the "in one life" challenges that I've had trouble completing, it seems that after you have that challenge activated for so long, it just starts counting your challenge kills regardless of your deaths. For instance: If the challenge is "Get 10 Headshot Kills in One Life", I just noticed that after failing to do it for so long (while having it activated) that each headshot counted regardless of me getting killed. So it made it a bit easier, at least I've experienced that. I'm sure it's the same for everyone.
