Do you sleep train your LO? If yes, how do you do so? If no, why?

I engaged a sleep consultant and sleep trained my lo at 5 weeks old because it was taking a toll on me. In the day, he only slept when being carried and at night he woke up every 1.5-2.5 hours. But I'm against CIO so I went to find out what other methods there were. Many people associate sleep training to CIO but there are gentler methods and yes establishing a routine is important. Once he was sleep trained, it was a breeze, he learnt how to fall asleep on his own and in the cot so definitely no regrets doing it.