It's attention, not money, we should budget

@mahgister 

You should be very proud of what you've produced with what you had to work with.  I can't think of a more relevant response to the OPs topic. 

(My reference to acoustical panels covering the glass in my wife's vehicle was an "attempt" at light humor.  I hope you took it that way?)

My own car is driven by my wife because i really put some day  acoustic stuff on the window of my car and refuse to start the engine listening music... My wife forbid me to drive since  ...I dont like it anyway...😉

it is a joke with a grain of truth here ...

In principle I agree with your premise. Execution is another element and for some the scale solidness when patients are tested and the perceived net result is not gained. The easier thing to do is throw money at the problem. 
I actually found that in my environment spending less on speakers was better. Around 20%. Moved that 10% to electronics and room 40/35 5% power and cables. 

30% room might be good if you have a dedicated listening room, but I think it's a bit much for a room that serves a multitude of purposes.... 

Maybe.  What if you keep the stereo in mind when selecting your home furnishings, and rugs, and maybe throw some panels on the ceiling?

My take…No doubt your room is very important.  Percentages are just a rough guide that may or may apply very differently to audio junkies.  They are most applicable to dedicated  room treatments or construction and may very minimally apply to living areas. Sooo many factors are involved that sku the percentages. In my living area working off a corner, valted ceiling, open access, built-ins, furnishings…very little can and needs to be done and it works out pretty well. Tried temp panels and drapery fabric with no improvement and ended up just using a bass trap in the corner behind my system.

Yikes… I know when shopping for home furnishings with my wife the stereo system does and will never take priority or even be considered or discussed.  i am enjoying my happy relationship and her tolerance as it is now 🤣.