Putting your newborn on a schedule?

Morgan • Mother, and wife. Expecting another baby girl in March!
My sister and I have newborns 3 weeks apart. We both breast feed. My daughter is 8 weeks old, and her son is 5 weeks. I feed on demand. If she acts hungry, I typically let her latch and feed her. My sister has put her 5 week old on a schedule. So, yesterday I'm holding my nephew and he's searching on me to eat and sucking his hand and crying out. I tell her I think he's hungry and she looks at me and says "there's nothing I can do about it right now he just needs to go to sleep" I actually got teary eyed. I feel that newborns cry to find comfort. Does anyone else put their newborns on a strict schedule that young?