If you need 80 shards, and drop rate 2% then you need (on average) to spend 4000 energy. So over 5 days, that's 800 per day.
We get 240 + 45 free a day which means we need 515 from else where.
480 can come from 3x50 refreshes and a 100 refresh (250 crystals per day).
So for 1250 crystals, you have 3825 energy to spend.
A full energy before event started (especially if loaded the 50s just before clock reset), or a little bit of luck, or an extra 100 refresh on day 4 or 5: and I can believe it would be totally possible for 1250 crystals.