If they really work at it as a profession who cares. It could easily turn into a full time job if you are raising troubled teenagers.
Some do just that.
Going back five years now, I knew of a lady whose blood children were leaving the nest one by one. She decided to go into foster caring in the local Florida area. She jumped through all the hoops, classes, bkg checks, etc. Did everything she could to start but the county here in Florida never sent her anyone. In desperation she had to find alternate work and took a job 20 miles away. Her last daughter at home had some issues. She got her license and one night went to get her mother with the car where her mother worked. In the end her mother got another ride home. Daughter while turning around on a dangerous highway got sideswiped and airlifted to Tampa General. Never to live a normal life again. Paralyzed, unable to speak, etc. Needless to say that family has never been the same. Husband lost work. Moved around the country for medical help for girl. Divorced now. They were such a blessed family, not hanging on by a thread.
Still to this day I blame the dcf agency for misleading that mom into pursuing foster care.