I was bfing and supplementing my twins. I was completely AWFUL at tandem nursing (maybe b/c of breast size??) so I fed one at a time normally & I had a 3 hr schedule. If 1 would wake up before the other I'd nurse him on one side and when he was done I'd wake the other to nurse on the other side. While I was nursing #2 I would supplement #1. I'd put #1 to bed and supplement #2 while I pumped for 15 minutes (I had to pump for extra stimulation for supply issues).
If they got up togeather, I'd nurse one and supplement the other beside me on the bed. After about 20 minutes I'd switch them. Once they were done their feed I'd pump for 15 minutes.
Either process took about 45 minutes to an hour and I got to sleep for 2 hours in between. So I would get 2 hours of sleep, an hour of baby care. 2 hours of sleep, an hour of baby care....
It was like this until 5 months when I gave up nursing. When I moved to formula full time they would get up once (sometimes twice) to eat and they got at least 1 bottle a night until somewhere around a year.