It is not a good thing to encourage, as falling asleep in your arms will lead to co dependency and to other bad habits and you will get no work done. If it is a toddler of two who just happens to fall asleep while playing with his toys, you can wake him up for his last bottle and diaper change and put him in bed. Walking around the house carrying a five month old baby who is fast asleep does not make sense. You have housework to do, errands to run, events to plan; you cannot spend all your time with the baby. Of course if you have a six month old infant and he has to feed every two hours, that is a different thing. He will wake you up for a feeding, you will breastfeed him and change him and he will go back to sleep.
Developing co dependency
An infant falling asleep in your arms and you carrying him around for an hour is not productive and will create fear in him when he is put in his crib, throws a tantrum and cries to be picked up, and you do so. Some people would call this a spoiled child, but he is not. The mother did this by creating the closeness and he is used to being with her; he has been inside her for nine months. When he cries and does not want you to put him down it is because he has become used to the long periods of time he has this luxury and that he is most comfortable there. This, however, is not good for you and the infant. You can’t have a child dictating his sleeping hours to you. And you don’t want to create dependency. If his behavior is not corrected early in life, your two year old becomes a three year old and four year old and will still cry when he has to go to bed at night. The next thing that will happen is that he will want to sleep in your bed. Even though two people are in the bed he wants to be in the middle between the two of you. Should you allow that? I would say not. Giving in to your toddler would be a huge mistake. The solution to all this is to spend enough time with your toddlers during the day, and let them spend alone time with their books and toys in their room before being put to bed where you will give them one on one attention.