And I can tell you from experience that knowing the right power settings and having your attitude under control you can fly a 172 with minimal trim. e.g. level attitude and 2300-2400 will deliver you cruise speed without overly strong forces you need to trim away. The same goes for pattern attitude speeds and flap settings - its a question of knowing the exact numbers by heart and not fumbling around to much. But I had a very good instructor.
Its different for a warbird like the P-51D but the 172, as a trainer aircraft, is very well balanced.
Thats the key point here.