Class 10 son wants to drop maths tuition after the mid-terms. Do I agree?

My son is 15, in Class 10, CBSE. He has gone to maths tuition three evenings a week since April. His mid-term paper came back at a level he's happy with, and now he says the school's revision schedule is enough and the tuition is mostly repetition. He may be right. What I can't tell is whether the tuition is the reason the mid-term went well. I only have his account of what happens in either class, and he obviously has a preference. I'd rather agree to a trial than refuse outright. If you allowed something similar in the board year, how did you set it up, and how did you judge whether it was working?