Everyone has their sweet spot. I kept pushing for more soil until I hit a point where I found that when I pulled the plants up after the harvest, the roots were not reaching or utilizing all the soil I was giving them, and I was lugging around a lot of water to keep all that soil viable. I had gotten to the point where I shoe-horned a 54 gallon tote into the (less than 2x4) closet I was growing in, it took up almost the entire footprint of the floor space. I could not fit more soil in there without boarding up the bottom of the closet door and just filling the bottom of the closet itself with dirt! LOL
I guess it depends on your system, how you water and how you drain. For me I found the point of diminishing returns, based on how long I veg for and how extensive my roots get. No till is how I garden outdoors, but my indoor garden works on a different paradigm.
I look forward to seeing how yours goes.