One formula feed, one breast feed.
Both mostly on demand but they both settled into a fairly predictable pattern.
With my formula baby, it was on demand, but if it got to 3 hours in the day, and she was awake, I'd offer.
With my breast fed baby, evenings and night were all over the place, but were bang on every 3 hours in the day. She only fed for 5-10 minutes (day or night, but did an evening cluster for a bit), and usually only one side at a time. It was very easy.
However, for both of them, I would also bring feeding forward etc if convenient. So to try and fit in a feed before a drive if I was meeting a friend etc.
I also didn't wait until my baby started crying, but only until they showed subtle signs of hunger. My first, didn't ever really cry unless she was ill (or in the car). If she cries for more than about 5m I knew she was coming down with something. My second went through a colic stage, but otherwise was also quite a low crier, albiet not to that extreme.