A whole lot....
That big dig didn't need to be that deep, but soil bearing requirements put us down that far. It's now been filled to the under slab height with clear gravel.
In hindsight, I should have just moved the whole garage about 10 feet closer to the lake, and had a step down rock retaining wall built. Definitely could have evened out the foundation step downs, and the excavation, and potentially lessened the amount of concrete.
This job has definitely been another "learning experience"...