Its pretty hard to teach infants to sleep at night sometimes. Having a fan in the rooms helps A LOT.I have had 7 children in my life. None have needed white noise. It becomes habitual and you're creating a dependency. It's like parents giving their kids melatonin to sleep. If you do it regularly then they always need it.
Teach your kids to get it together.
Helps them sleep 8 - 10 hours easy.
Source: I have 3 under 2.