This answer is going to vary based on a few factors.
1. Learning speed
2. Learning Disabilities
Most kids that need tutoring will benefit from one-on-one instruction.
At school, instructional pace is based on a certain curriculum, not the needs of each individual student.
With one-on-one tutoring kids can get the exact help that they need at the exact right time. This allows growth to happen quickly.
If your child has been diagnosed with a learning disability, it may take more time to learn a new skill in mathematics. This is because it takes longer for things to go from short-term memory to long-term memory. In this case, your child will benefit from more repetition.
Another factor is consistency.
Sometimes life gets in the way of students being able to show up for their tutoring sessions.
If students miss too many sessions, then it becomes harder to close the gap.
The more consistent we both are, the better results your child gets.