Another thought...
Concerning feeling sore or feeling you've worked particular muscles, you have to remember that a lift is only as strong as the weakest muscle involved in it.
An isolation lift strictly performed uses the same muscles throughout the movement, a compound lift calls on different muscles throughout. For example in the bench press, as you push from your chest it's first pecs and then as you lockout, the tris; in the squat, from the bottom it's your glutes and hamstrings, as you pass parallel it starts to be more your quads.
So if one muscle group is relatively weaker, that'll be the muscle group that's worked the hardest. It'll tire first, and is more likely to be sore.
For example, my glutes and hamstrings are much weaker than my quads. So when I squat, I never get sore quads but often get sore glutes and hams. When I benched a lot, my pecs were weaker than my triceps, so I often got sore pecs but never got sore triceps.
Looking at the muscle pairings around, we see that it's most common that people have weaker glutes/hams than quads, weaker pecs than triceps, and weaker backs than biceps. When doing the compound lifts, the people then wonder if the stronger half of the pair is being worked at all. It is, it's just that the weaker half is so much weaker that it gets exhausted before the other half.
Eventually as you do these lifts the weaker part comes up in strength, and all parts tire and hurt equally