Well, my way to play it is: as soon as you log in to PPS with a Shards Event up, first of all, go fight 1 opponent, to start Focus Regen, and then go to Ngacha and ropll it until you'll get N SEC. (go do 1 more fight if you are unlucky and didn't got an N SEC in 10 min, and your Focus is already full again, then continue, until you'll get an N SEC) and go roll that E-gacha before that if you have some tickets - to get bonus shards from the very first fights. Then, you can probably want to make a timer in your mobile device (cellphone, smartphone, or even your electronic wrist watch if you use one - whatever is always with you and have timer function) to remind you that Focus is already full, every 30 minutes, incase if you'll get distracted by some other stuff, like Web surfing, gaming, some IRL stuff, whatever. And don't forget to re-set the timer every time you use Focus in PPS. Also, don't forget to use the E-gacha ticket you'll get in teh middle of event as a daily login bonus, as soon as you'll get it (and, of course, use Card Reveals when using E-Gacha, and choose Slayer Cards if you'll get them in the 6-pack E-gacha gives you.).
Another good idea is to calculate the amount of shards you need to get / fights you must win / hours you must play every day, to get as much shards as you need. I'm not very good at maths, but i can tell you that, since Focus regens by 1 piece every 5 minutes, and you need 2 Focus to do a fight, you can do 3 fights every 30 minutes, which is 6 fights every hour. For me, with my current 4 shards per fight, this means 24 shards per hour. Of course, sometimes you'll lose a minute or two, and make less fights per hour, but you will still sometimes get Raw Puddings (full and halves) as daily win streak, and other streak/achievemnts rewards, so they will help you fix that. Btw, since you will, probably, not get enough Shards in time anyway, and will eventually have to use some puddings to get more shards to be able to trade for the girl cards you need, it's a good idea to do that not on the last day of / few hours before the end of event, but instead, use some puddings (especially those Raw ones, since you can't keep them forever) every day, during, say, last hour before the daily restart (Shards Event streak counters reset one hour after Daily Missions reset, when you usually recieve Daily Login Bonus), to reach the nearest/best Daily Streak reward. Say, if you play PPS 10 hours a day, and don't let your Focus stay full, you'll get 60 wins per day, and by using a few more puddings, you can bosst it up to 80 wins, which will give you an extra reward of 5 pieces of SR Wild Card 3 - which is +15 levels on any SR card, while still earning you those extra Shards you'll need to get the Shard girls you want. 100 wins streak reward, of 3 shards doesn't worth it, so don't try to reach it if you end the day with, like, 60 shards, but if you somehow manage to make more than 100 wins during a day - it's a very good idea to try and reach that 120 daily streak, to get an extra R gacha ticket. (trying to reach it on puddings with like only 60 normal wins still hardly worth it). Next good streak rewards are 175 and 200 wins (Ex Wild Card and SR gacha Ticket), which is, probably, only for those who burns alot of puddings every day, so don't bother trying to reach them - or do try, but during the last day of event, and only if you miss really alot shards, and really want to get the girls right now. Also, keep in mind, that those Raw Puddings only live like 24 hours since you accept them from the Gift Box, and i guess they sometimes vanish even faster, but they can sit in the Gift Box for pretty long time, so i suggest you to not accept gifts until you are ready to make your final rush at the end of the day or event, and use those raw consumables as soon as you accept them, to not forget to do it later, and only accept as much as you need to reach the desired Daily Streak Reward, and save extra Raw items in the Gift box for the next day.