I'd say, realistically, it takes about 3-4 hours of dedicated effort to level a character from 1-20, if you grade it up with 1/2 bronze matches (if you're team does really well or it's a +25% xp weekend, you can hit Lvl. 10 in 1 match) then switch to silver (I don't think gold gives enough of an XP boost to really make it worth it) and consistently doing unknown/unknown (though it might be faster just farming Geth on FBW on gold- I don't like to do it that much, so it might be faster, and if you're good you can do it from lvl 1 with little difficulty).So, for the sake of argument and to pad our numbers a bit, let's say 4 hours to fully level and fromote. That's 30 N7 every 4 hours. Unless my math is wrong, that's about 169 runs to hit 5070, or 676 hours, or JUST over 4 weeks. It's possible if someone's always playing the account, but on top of the time spent there, they'll also be getting XP from character unlocks, and if they keep only playing one character and leveling up the others with cards and promoting them when they have a chance, it would shave some time off that number, probably enough for it to be possible for one person to do it around sleep (but not a job too, I don't think). Of course, they could always just buy a bunch of packs too, so they could really have been playing for any amount of time and have that rating.
Yeah, N7 is broken.