Is room treatment a science?

Yes.  Room acoustics is a science and is written about by much smarter and more accomplished people than I.  I like to read Floyd Toole when I want to pretend I'm smart.  Otherwise I ask GIK Acoustics for advice.

I will say after lots of measurement and experimentation that treating your room well is never a mistake. My room treatments have outlived everything else I own. It is by far more productive to treat the room than start swapping speakers, cables and amps. 

Great ideas!  The project begins. I thank you!

Trial and error. Big problem. It’s not really science. What’s required in order to have a glimmer of hope of finding the absolute best solution for room treatment is to employ a SPL meter and test tone generator such as 315 Hz, for example, on a test record or CD. That way you can precisely locate the problems in the room, a great many. The primary acoustic anomalies in the room are sound pressure peaks more than 6 dB above the average sound pressure in the room - e.g., room corners, standing waves, first and second reflection points, sound pressure peaks behind the speakers, peaks in the 3D space of the room.

Room echos can be easily identified using wood blocks and walking around the room clacking the blocks together or clapping your hands 👏  until you hear the distinctive echo. Once you have treated the room, use the speaker placement track on the Test CD or LP to find the absolute best speaker locations. If you add more room treatment at a later date, tiny little bowls, Mpingo discs, whatever, you need to reestablish speaker positions as room dynamics will change. But, gentle readers, trial and error for room treatment - like its cousin speaker placement - is like trying to solve X number of simultaneous equations in X + N unknowns.

Yes room treatment is an actual science, if you look at recoding and mixing studios you will see.   But it is very straightforward and pretty easy to do. 

As stated above, GIK can be a good resource if you need a consult and product.  If you have an idea on what you need, Audiomute is another good and affordable product line.  If cost is an issue, most all of this can be a DIY project.  Don't over do it, stick with some fundamentally accepted treatment suggestions to start and go from there.  Good luck in tuning your room.