Originally Posted by A Medium Bear
I just unlocked the achievement! Can confirm that they don't all need to be done in one run.
FYI, I unlocked it on my 71st Gold (48 Story/23 Strangers). The 70th Gold was completed in part, in other words, I got a Silver but had completed the other challenges and the 71st was completed as a Gold (I did all challenges at once).
Perhaps just make sure you completely Gold a mission on your 70th one. Not sure if it will unlock if you pass 70 although I have reason to believe it will as is my case in point.
Best of luck!
That was quick, nice work. I've only done 15 missions so far but they're easier to 100% than the missions on TBoGT.