What’s the secret?

To those that have babies sleeping 6+ hours...what’s the secret?! I know part of it is developmental but what tips do you got? Where does baby sleep? What’s your routine like, how much does baby drink before bed...anything else?? My baby has really only given me 4 hour stretches with the occasional 5 but I believe we are going through a regression, the last few weeks we’ve only gotten 3 hours maxx. I should mention he’s got reflux tho.. mamas tired but my sleep is so messed up right now!