i had no monitors. i am a light sleeper and husband is rather heavy sleeper. although there was an empty room between our room and nursery, there were no issues of not hearing baby cry. our doors are never closed. both of us would usually get up to tend to baby together.
We prepared two baby monitors for our first born, but we did not exactly use it because she is sleeping in the same room. We tried to put her in a different room, but could not help to wake up multiple times to check on her (failed after 1 night).
depends on your home configuration, if you can hear baby cry if you step away from the room?