Depends on age
My baby girl is only 9 weeks old. I don't normally let her cry it out unless I'm using the bathroom and I absolutely can't get to get at that moment. Normally when she's crying and fussy its because of a reason. Such as a poopie diaper or she's gassy and her stomach hurts. However, when she gets older and is able to self soothe, I'll probably let her cry it out more. I think it just depends on the child, the age, and what the needs are for mom and baby.