My spark quest account is really cranking as of late, I'm the second largest mine holder of any Upland player in the layer 2 game by quantity of mines and I'm not closing in on being one of the top maxed out factory holders as well.
When you max out a factory, your factories begin to produce new PWR crystals for you each day. I am now producing 156x PWR crystals every single day or enough to make an additional 15x maxed out factories every day. That's creating a snowball effect for me now that's really helping to increase my production and really helping me stand out above the rest.
I even made some sales of PWR crystals while I was away on a 5-day vacation adding to my abilities to create passive income with Upland.