So we put our son into a group tutoring class that ran from Sep - Aug year 5. It was one 3 hour class a week during term time with some homework. Maybe 2 hours a week. So one evening plus some of a weekend morning doing homework.
Once the class finished, we tutored ourselves/used Atom from Aug up to exams in Sep/Dec. We had sep grammar exams, so during the 4 week august hols he did 2 - 3 hours a day. Once back at school sep- dec he did probably one weekend morning.
Our son is at state school, with very little homework and work also fell back during covid. He is one of the top in the class so isn't really challenged by some of the work in class esp in maths, the work is completely different from 11+ in terms of speed and complexity (though it is largely based on the syllabus studied). He also isn't really an independent grafter and can work slowly and lack focus/accuracy. So he definitely needed the tutoring to bring his work up to the standard required for 11+. Though he would not have said he loves revising, I think he actually enjoyed a lot of the process. He has gained in confidence with his work and liked the more challenging maths work and essay writing.
With this level of revising, for a child who has usually been achieving 'greater depth' at school with no extra work, he has got through to interview at some schools but not all and he passed though the Sutton grammar 2 stages but didn't pass through the first tiffin exam.