I'm reading a biography of Jane Austen, and I didn't realize until then that sometimes the use of a wet nurse included separation from your baby for months, even years. In Austen's case, her mother breastfed her for three months and actually never left the bed during that time. Then, after all the intimate contact and bonding time, she handed the future author over to a wet nurse in the village, and Jane lived with her until she was almost two years old! The biographer wasn't even sure that her parents even visited her all that often.
I'm not sure that always happened, but I just somehow assumed that the wet nurse either lived with them or spent the day over at the baby's house. To me, that puts the older practice in a whole new light.