OP, you say, "Every professional installer (either for the home or the studio) measures, tweaks, measures, listens, and gets it right."
My experience is otherwise. I've owned systems from 2 figures to 6, and every one of them was better than what the pros did in a public building near me. 10 days ago I was treated to one that was even worse.
Of course there are experts who know what they are doing. The famous Cox, who did the research on room dimensions is a superb example. He found that most rooms are just plain bad, and that the difference between good and just OK can be as little as 2 cm in one dimension. Ignore the science at your peril - like some pros it seems.