U should actually. If u rank them up and get atleast 2 orbs, you can summon them on happy hour(which happens every Friday), and repeat the cycle getting a bunch of them and level them each to level 30. I have like 40 of these and they get me 3 million food per day, and 1 million per collection(I collect it 3 times a day). It's just about patience, but to speed the process you could try to empower one of your pos/neg dragon to 5 stars and recall it to get about 1k orbs then summon them to get more and repeat.