Some trainers are meant for children just learning to use the potty, while others are made for children who are using the potty with occasional accidents. (the-cloth-diaper-connection.com)
I read that parents should expect occasional accidents even up to the age of 7 or so. (babycenter.com)
She will signal by the door when she must go out, but she does have occasional accidents inside. (anewstartonlife.com)