I had a part time DCG that cried all day for FIVE MONTHS!!!! It was not fun. Her parents were not concerned and felt bad for me but said she just had to get used to it. I think when they are part time it takes them longer to adjust. I gave them a one month warning at 4 months and it miraculously stopped. She is still my most "passionate" DCK but is a happy girl now most days!
I set part time at a minimum three days a week.