If you are looking at this page then you are considering or have already started tuition for 11+. It is a daunting time for a 10-year-old to go through. Are Grammar schools worth it? You wouldn’t go through it if you didn’t believe that.
The education your child receives from school must not be underestimated because, without it, they would not have the foundations for a tutor to build on for the 11+. The more gaps there are in their foundation the further back and the longer the time needed with a tutor.