Is grounding a teenager for bad grades an effective tool?

I just had a huge argument with my husband over my discipline of my daughter. She is in an expensive prep school that he is paying for, she is on acadaemic probation. They had a snow day today, so I let her go to her friend’s (honours student) to study. I let her go to a birthday party Saturday night but made her come home at 8. (It was a sleepover). She is staying after school every day for study hall, being mentored by other students for their honour society hours. I am working with the school to know her assignments and keep on top of her to work on them. He thinks I am too easy going with her and should have kept her grounded for two weeks. I can’t stand the arguments with him about it, he thinks she should be confined to the house and her room until two weeks are up. Does grounding a 14 year old over grades help at all? Her behaviour otherwise has not been a problem.