Depends....I was always taught if you can SAFELY remove the seat with the child in it (immobilized-padded etc)...go ahead. If the child needs intervention (ie. airway control etc) then remove them. It all depends-is it intact? Compromised? There is no 'rule'. I was taught to use it as a tool if it helped. If not.....get rid of it.

Personally, I have left many a child in it to get them out. Made things easier and smoother. I know of others that can't wait to get them out of it.