How Competitive Are Sports

I know that the intensity increases at its highest point on game day because you want to win, but how competitive can practice get when you go against the same players everyday of the week on every play. The coaches want you to play as if you are playing in the game and do it correct as well, but doesn't it get harder in practice everyday because the person across from you knows how you play and can use that in an advantage against you. I understand that you progress your skills in practice as the year continues but when players go hard in practice the speed might be the same but its a different feeling in practice.