for breastfeeding, you should feed him base on this demand, not look at the clock and feed him.
every baby is different, some can skip the midnight milk and some still need like my baby.
for your case, if you feed him every 4 hours, and if he eats well and a lot for every feeding, and gains weight well, it is fine.
I always feed on demand even my boy is 19 months now. When he was 3 months, I fed him every 30 mins. After 3 months, I fed him every 2-2 1/2 hours. At night even now I still feed him when he is sleeping!!!
bb should be feed on demand! If he is sleeping, I will wait till he wakes up. For your case, if bb gains weight, this's ok! Don't worry! bb will eat hard when he feels hungry!