I agree that A/B short term listening skills can get in the way of choosing good speakers. This strategy can easily work against you. By moving your minds eye (ear) around the sound stage you are evaluating things like detail, transients of one frequency or instrument, or decay of an instrument or sound. While these are important aspects of performance they do not add up to great sounding speakers. This can add up to analytical, highly detailed, fast, and lean sound with great bass and slam. The gestalt of these can completely be devoid of music, warmth, beauty and natural emotional involvement. Great scientific instruments for anlysing sound, but not for reproducing music.
So, there can be a downside. Some folks, from the very start get this and pursue the musical center... but in my experience they are few and far between and start (virtually without exception) with tube equipment and stay with it. I was not one of these people... I learned the hard way by constructing an incredible detailed system which was emotionally involving. In my defense I have heard many much worse... and much more costly.
The longer term listening... A/B over a week (my preference)... but a couple of days works is the only way to access what is important. How much you are drawn in. and the sound field... you almost discover the attributes in reverse of short term... by starting with the gestalt and then working in on the major strengths and weakness in a natural priority.