Thoughts on turning the baby monitor off?

I've had many people telling me once their baby's got older they just turned the monitors off at night and if they really needed you you would hear their cry just not the night time babbling. So I looked it up and found an article talking about after 4 months you can turn the monitor off at night. I mean it sometimes makes sense because normally when I intervene when he wakes up at 3am he won't go back to sleep but if I leave him he will. I just want to hear thoughts on this, and from moms who have multiple kids when did you start turning the monitors off?