Ethan, this has nothing to do with million dollar studios but with design and planning from the scratch starting with dimensions, measurements, and even acoustical models if required. (if the client can afford it of course!). Not to talk about HVAC and electricity.
This has nothing to do also with who is in the studio. You could put Bob Clearmountain on my bedroom and me on a top professional studio and he would for sure get better sound than me. That does NOT mean my space is considered professional. I separate spaces from people who use them
You cannot compare a typical size bedroom with a large control room. What I do in a typical bedroom ? Maybe not that much different than you do (I do like to add a bit of diffusion) but I don't consider such place acoustically speaking similar to a professional control room. If I'm asked to design a studio from the scratch there's much more in-depth way of thinking.
Glenn, yes I know what waterfalls are and I noticed that. Not enough in my opinion for a good time analysis.