I'm a new dad with a 1 month old, and my wife and I have done a TON of research on development, nutrition, etc. We've read the books "What to expect when you're expecting" and "What to expect the first year," talked to the OB/GYN as well as our pediatrician, my wife's sister (who's a pediatrician herself) and visited tons of websites about babies. Everyone says different things, from "It's good to let babies cry to clear the lungs of mucus from when they were in the womb," to "it's impossible to spoil a baby within the first year." My sister-in-law didn't put her first child in her own room until about 6 months old. Their second child went into her own room at about 6 weeks. I think you should learn to recognize your child's different cries and base your decision to either leave them to cry or to comfort them based on the sound. If your baby is in pain, it's cruel to let them wail for 20 minutes and suffer. They may remember it later in life and never move out of the house!!
If I ventured in the slipstream between the viaducts of your dreams
Where immobile steel rims crack and the ditch in the back roads stop
Could you find me? - Van Morrison, "Astral Weeks"