"Is it neccessary..."
No, thats just what I used. You can add as many electrum hourglasses as you want. I recently added another two and recieved good results. This deck is for Halfbloods, so you really don't have to go really fast. They never seem to summon anything your oty, 2 RoFs and a Fire Buckler can't handle. The point is to have moderately long fights, but to save a miracle for the end so that you can triple your earnings. A level 5 is supposed to give you around 40 electrum, according to the little blurb in th game. This deck gives you 140 electrum per win, which are usually Elemental Masteries because you have so many miracles. the fireflies have to be un upped so that you can generate large amounts of light quanta for the beginning of the game when you have low hp and you have bad draws. The end game needs to have a miracle to make everything worth it.
I think I added a rustler when I was really strapped for Life quanta, but I have multiple copies of cards because I don't expect them to survive. I might make like 6 fireflies then have it killed. To me, this strategy works much better because you don't have to wait for a quint because you are scared of losing your only source of light quanta and miracles.
EDIT: there are supposed to be 2 un-upgraded FFQs not 3 and an elite one.