Who is "them"? 
I saw that claim a lot, but rarely substance to it. As far as my experiense, nombers were/are often lopsided at reset because of A) the reset being a result of an often massive numerical superiority of one side in the first place and B) because the "losing" side members logging off in disgust.
The majority of players are actually quite country loyal, even when switch times were down to 2h.
I always remembered the whining of people switching to the winning side to get the perks
I'm sure quite a few logged off in disgust, especially since when we had 2 LWA's one arena heavily favored one country, where other arena favored another and so on.
I personally prefer the single arena, where no country has the advantage period, if you were unlucky in the old days with 2 Arenas where more then half of your squad was in one arena, you had to wait it out to get into that Arena which generally was full, or go to the other arena and fly solo.
That being said - Back on the 12 hour Time shift - What purpose is it for now a days? If someones going to spy they will simply be outed for it same as vulching shades. Besides a few named squads that switch countries every tour, and a few random people.
I wish we had a pie graph to dictate how many switch countries per day, it would better understand what exactly people are motivated by.
I always enjoy the whining "A spy is in our shore battery and its not firing!" If someones going to use a shade they will simply keep it on a country without a squad tag, HTC is going to deny someones $15 to play timid.
