When I was in the Corps, I had a SSgt we all thought was a bodybuilder because he had a huge chest, shoulders, & decent arms. His Lower body wasn't as near developed. We asked him all the time on how much he lifted & what his routine was....& he would swear that other than push-ups, pull-ups & dips, he rarely touched the weights.
One day we saw him in the gym, & asked me to spot him doing 225 which he barely got 4 unassisted reps & I assisted him for an additional two. After the set, he smiled, kind of chuckled at himself & said "I told you guys I don't hardly lift weights". That was his heavy set. He then unloaded the bar & went upstairs to do some cardio.
Personally myself...I found it extremely easy to put alot of size with push-ups. At that time, I did alot of push-ups every day to the point my chest grew out of proportion to everything else.
Then again...I see tons of guys do reps after reps of push ups, & never build a chest at all. People like myself, I can do push-ups & totally fatigue my chest muscles. Where as when I perform a bench press, my shoulders & arms fatigue first before my chest no matter the angle I use, the grip, or elbow placement.