Absorption, Diffusion or a combination of it all?

According to the pro's pros, without a proper analysis of the room, you are guessing, and may make the acoustics worse.

I have experimented a lot over the years with acoustic panels, mostly from GIK. I have used both ears and REW measurements to accomplish what I like. I am currently all GIK. What worked for me best is:

Side walls: Combination of 242s and Alpha 4As

Ceiling: 242s

Front wall (behind the speakers): Alpha 4A and 6A

Bass traps: Alpha 6As (my corners are scaled, with multiple outings, so I can only “tuck them in” with overlapping Alpha 6As)

Back wall (behind my listening chair, about 10’ behind): Alpha 6As

I like the Alpha series a lot. Very versatile, as they are a combination of absorber, diffuser, and bass trap: https://www.gikacoustics.com/product-category/alpha-series/

All…thanks for your thoughts! 
I watched the video and it makes sense but isn’t easy to implement, no room is ideal as far as wall space, ceiling, windows, doors, etc. Good as a guideline though.

So since I’m already using the GIK 242 and 244 bass traps in the corners, I’m thinking to add a set of A2 Alpha Pro, exactly the same design pattern @thyname has in his room. Decent amount of absorption and enough diffusion. I don’t want to completely deaden the room. Still researching. Keep the thoughts and suggestions coming. 

OP

If you look at my virtual system you can see how I implemented the video. Interleaf diffusors and absorbers, pretty simple. 2D diffusors in front half of the room and 3D diffusors in back. Absorption on the back wall directly behind MLP with diffusors to each side. 

I initially started with 2 GIK quadratic diffusers on a shelf in front of my tv screen between my speakers. I liked the results so much that I purchased two more and put them atop the original pair.