It depends why the tutoring is needed.
I've tutored children for entrance exams and what I'm being paid fir there is to go through and explain the questions found on papers but fir that to be worth it the child gets set additional work between sessions. I've also tutored struggling children who just sometimes need things explained a different way so it clicks or some extra focused practice. I do set them weekly exercises and drills but sometimes just a bit of one-one dialogue is enough to help them understand and once they've understood they're back on an equal footing.
It's possible to tell a tutored child though, especially a badly tutored one. In maths they number crunch what's been drilled into them, in other subjects they lack a certain spark - they know their stuff but for a tutored child that's often where it stops.
For your average non-struggling, non-SEN child extra subject tuition is no more than doing lots more Bond assessment papers. For a child who struggles to understand a specific subject the way it's taught at school (often kinaesthetic learners in maths IME) tutoring helps it click and for an SEN child who isn't supported tutoring helps provide them with strategies for coping on their own and ways of attacking the problem.
At the other end if the spectrum a very bright child shouldn't need subject tutoring but might need exam technique. Extra-curricular academics like Latin/an MFL or something else not taught in schools are better because it stretches them in a different way and gives them the additional knowledge they crave without sending them whooshing through the curriculum and ending up bored at school.
That said if every child is effectively doing an hours extra school a week with a tutor that standard becomes the norm and even an above-average child in terms of natural intelligence will fall behind because school will move faster, leaving the consolidation to the tutors, and the untutored children miss out.
I hope that makes sense. I think my overall answer is yes, you can tell and yes, it can be worth it but it's not necessarily a must or a desirable thing. Parental input on a daily basis beats an hour of tuition hands down.