If you are lifting lighter because it's the only way to get all the sets in then reduce the number of sets. Two sets is fine on any excercise. Don't do super heavy weights until your muscles are decently adapted to the load. But once they are then yes, two sets of eight is great.

Way too much chest I agree. You know that two sets of benchpresses per week will keep your pecs and triceps' in decent shape. All this "incline" and "decline" and "fly" and so on exists mostly because it's easy to see our chests in the mirror. I'm sure that if the eyes were in the backs of our heads it would be the back exercises that get all the attention.