Yes I agree that student B would do better too. Somehow I feel that I'm more productive if I split my practices rather than practise in a long stretch of time. Even though 4 hours a day isn't considered very long if the practice times are split up, but given the same abilities and all other conditions, the same thing spread over a longer period of time would have a better effect. I don't know if anyone else has this feeling, but sometimes I feel that I improved 'overnight' even if I didn't do any practise. I practise in the day, and maybe certain areas are not technically very right yet. But after a break and I try again the next day, it somehow got better miraculously.