I remember running into this idea when I was taking care of a colicky infant. Baby carrying slings and wraps seemed very popular among new parents. This article covers some of the evidence: https://www.theguardian.com/lifeandstyle/2005/jun/08/familya...
In my experience, baby carrying is great but some babies just cry. My first child was held constantly, and we spent every evening bouncing hard on a yoga ball with her, but it wasn't enough to fully quell the crying.
Baby sling / baby carrier is just miraculous. First daughter with second wife was crying a lot and we had to carry her much. With the sling you can basically carry the baby and still have the hands free and keep on with your stuff.
You also have to learn to recognize the stages of sleep. Hold the arm of the baby up and down. If the arm remains in the air, this is light sleep. If the arm feels heavier and goes down all the way, this is deep sleep. Only then put the baby into the cot. This is quite important to know.
In my experience, baby carrying is great but some babies just cry. My first child was held constantly, and we spent every evening bouncing hard on a yoga ball with her, but it wasn't enough to fully quell the crying.