so pec shape is genetic to an extent but weight training increases the mass so it'd be logical to state that weight training dramatically influences the shape of your pecs. In regards to the upper pecs i just want to build up my upper body more so i have that symmetric line from shoulder to shoulder. Upper pecs also look nice with a shirt on and off.
in regards to the decline i think i'll just add them and remove the extra 4 sets of incline dumbell i do along with the 4x incline bench. It's just a concern i have about the lower pecs turning into massive bulges of muscle tissue.
Actually this is what i do on chest day, someone help me out:
4x 8-12 incline bench
4x 8-12 dumbell incline press
4x 8-12 flat bench press
4x 8-12 DIPS
4x 8-12 FLIES
thats what 20 sets? is this too little or too much? really, i just want something that'll hit the pecs hard and lasts all week/actually makes them look nice (I'm doing 1 muscle group a day)