How long did you keep a baby monitor in your kids' rooms?

I only kept it in for about a year and a half. I have friends with kids almost four and I was surprised to find that almost all of them still have the baby monitors turned on. My friends who are having a second intend on getting a new monitor so they can listen to both kids rather than just pass the old one down to the new baby.

It just so happens that my one friend I know for sure didn’t have a baby monitor lost her daughter in a bedtime related accident, but I’m fairly positive that the way she died would have been very quiet—she locked herself in a tiny airtight box. Unless it was right next to the monitor, I don’t think anyone could have heard anything.

Anyhoo.. what’s reasonable? Did we let go too soon?