Same as snacks, I have heard it can go either way.
Perhaps your supply is less towards the end of the day, this is a really common problem. I've had this and I found that a couple of days of taking fenugreek made a huuuuge difference and I could actually feel that my boobs were still fullish at the end of the day. I was hell-bent that DS wasn't having any formula so I tried quite a few things and that's what worked for us - maybe worth a shot, it can't hurt
Oh and I also started offering him both boobs for that last feed - and the same week I started doing that he started sleeping through the night and has been doing it for two weeks straight now!