@Mpsafranski
Indeed, the Geddes approach is what made the most sense to me when it comes to Subwoofer placement. There are many ways to skin a cat, of course, but the seemingly more dogmatic approach of enforcing symmetrical placement, corner loading, front loading, 1/4 wall, 1/2 wall, etc... doesn't take into account that
every room is different.
I had a situation with my mains creating a huge suckout down low because of the symmetrical arrangement. I changed the alignment of the Front L Speaker by no more that 1.5" in it's floor placement, and rotated the toe-in angle just a hair, and boom: that suckout was gone. No need for EQ solutions to fix something which the application of a little science and common sense could.
That fix was possible because I took some time to learn about room measurements and acoustics. I understood some basics of what happens when a soundwave interacts with itself at the 1/4, 1/2 or full length of that wave.
I still haven't done a full measurement of my subs, but the metrics I do have to work with are quite acceptable. I came by my placement choices by doing the Crawl, I kept my mind open to letting the room's acoustics determine the best options, and I adjusted slightly from there as warranted by the limited measurements I had.
Both Subs and Full-range towers are all slightly different measurements from the walls and each other, and from my LP. Through placement alone, I have taken care to avoid creating nulls and cancellations. Do they exist, still? I'm certain they do, but not where it matters!