We did a combination of not responding so quickly to him (DH to blame there, so I did it while he was away!) and him dropping them by himself. If it's any help, here is our rough feeding schedule from that time:
3hr EASY:
7,10,1,3,5,7
4hr EASY:
7,11,3,5,7
He started to not take too much at one of the day feeds (an afternoon one, I don't remember which) and at that point he also started to go longer overnight. It was as if he needed to get to the point where he could fill up to go long enough, iyswim.