If you play same tactic same order same formation no matter what, and obviously it work, then what is the purpose to try to counter your opponent formation. I have to say that personally I have noticed two things: if I play the same formation for several game with same players( condition that I do not have numerous injuries) my players are getting higher stats, therefore better results ( like reel soccer you get used to your teammate and then better fluidity) but I also noticed that changing formation( the most important maybe is to get the right order with the formation including the opponent formation configuration )I have good result too ( also like in reel soccer when coaches changes tactics)...... Anyway it is not possible to replay a game to check the impact of changing tactics Vs keeping same formation then it's kind of like religion..... A question of belief!!!!!
Ps: maybe the only way to have an idea is playing friendly game over and over changing one parameter at a time ( and even then .... Forme, moral, change in quality...etc will affect the result)
That leave in the same questioning than the beginning...... But after all .... It's just a game fortunately real life is not like that...... or maybe it is!!!!!!!