Originally Posted by JSensei

It's 1600 shards to get all three. If you got the SR card from being in the top 1000 and the new N card, that means you would need about 400 wins. That's rough but doable. Easily doable.

Well not easy you do have to stay on top of your game and not let focus stay full too long. It's 4 days worth of playing (6x4x24x4=2304 shards[6 wins per hour x 4 shards x24 hours in a day x 4 days]) to get the cards with extras. But sleep will rob you a few of those. That's with only 6 hours of sleep a day (24 hours) of missed opportunities for me. 6x4x24=576 missed shards. (1728 total without pause for anything other then sleep)
if you only have the N-slayer it's harder (6x2x24x4= 1152 shards). You will get at least 2 shots at the other slayers because you get an E-gatcha for logging in, and one from consecutive wins. you do get a few for streak/daily wins but not enough to make a huge difference.
I will get a third shot because my monthly E=gatcha will arrive before the end of the event. Of the 51 cards in the e-gatcha box I am missing 16 (that's 31%) so I have a good chance of getting at least some missing ladies.

Happy hunting.

P.S. Yes, I do agree it's a poorly thought out event.