here's the skinny.
You can work sternal pec and clavicular pec to different degrees. However, flat bench activates both maximally. Switching to incline doesn't emphasize the upper, it just disengages the lower, because one of the functions of pec major is bring the arms down and in (that's how chest dips work).
So declines aren't really that necessary. I mean if your sternal pec is chronically overdeveloped relative to the clavicular, sure go for it. But there are a good deal of people, myself included, who have good upper chest despite only flat work.
You can work sternal pec and clavicular pec to different degrees. However, flat bench activates both maximally. Switching to incline doesn't emphasize the upper, it just disengages the lower, because one of the functions of pec major is bring the arms down and in (that's how chest dips work).
So declines aren't really that necessary. I mean if your sternal pec is chronically overdeveloped relative to the clavicular, sure go for it. But there are a good deal of people, myself included, who have good upper chest despite only flat work.