I wasn't able to down enough players I think. I didn't know they raised the number significantly higher each time so I ran out of the ones that were easy for me :T
Not sure if the game told me that beforehand or not, but for someone who's kinda crap at MP like me, it was a death knell, lol
I'm crap at this MP, so if I can do it, you can do it.
For my 5 100%s I did downs , executions, gifts, healing and i'm going to do healing for my 5th and final one.
Those should be easy. If you get to your 3rd day, though, and you're not going to get it done because the match is going poorly, you can hit the playstation button, close application, and you'll be back to the start of that day when you get back in. You shouldn't have to do it, but it's nice to know the option is there.