@emergingsoul I don't where anyone gets their information as to what room dimensions work best, here is a rather long article that explains the theory behind one calculator that shows how any combination of L x W x H of a room will affect your the best possible sound. This is only a start as acoustic treatments will play an important role in any great sounding room. The whole story is here:
https://digistar.cl/Forum/viewtopic.php?t=557
If you just want to jump straight to the calculator, it's here. The idea is to have the little dot end up in any area that is Black (best) Grey (good) and white (avoid).
https://www.acoustic.ua/forms/rr.en.html
The findings of this calculator are proven when the same numbers are entered into other accepted programs. I believe this calculator simply fine tunes the results. This calculator does not agree with some of the suggestions already given. I'm not one to say who is right, but it's an interesting read. IMHO. Cheers.