I worked in day care for 12 years. The ratio for up to two years old is 1 adult to 4 children. I opened in the infant room and sometimes had 10 infants/toddlers before the next teacher arrived. It was usually only for a very short period of time though and they were all eating breakfast. But yes, it is difficult. You're holding one getting them to sleep while you have your foot on the bouncy seat rocking another one. Sometimes I'd have two in my lap and two at my feet. Wonder why I don't have children of my own??? LOL
I have to say though......after I stopped working in day care and started at a desk job.........I've put on 50 pounds!!! Those kiddos kept me skinny!!! There are the difficult moments but then you see a child accomplish something that you helped them learn and it makes it all worth it.