Depends on what you expect from the tutor.
If a child just needs to brush up on some skills to fill in the gaps (not learnt or understood or even taught at school) then a tutor to help cover these would be fine.
But if a child is struggling generally on "normal" subjects taught in school, the pressure will be greater at a good secondary school, and consideration would need to be taken into account as to whether the child would cope.
You would have to look at what the school offered, and how would they help the child and whether the child would benefit from private tutoring.
Some kids do respond better with one to one tutoring - they find the classroom scenario too much.
I am sceptical about paying for tutors, we did for a term because DC was bored at school and had lost motivation, the tutoring switched her back on, but the tutoring was promoted as a one-one but the teachers actually had four kids to work with at the same time.
We use online tutoring programmes and online education sites/schools and play games to learn about all sorts of stuff and this works well for my DC
There is a lot of demand for private tutors, and it seems to be from parents that feel the school isnt doing enough for their kids. A lot of kids do seem to drift through school and are not stretched to see what they are actually capable of.
Even on this forum there have been lots of requests and questions about tutors.