Geogra
In Year 4, she did around 4 hours a week, but less during periods when she had project work to do for school and not so much during vacations and not much at all between Yr 4 and Yr 5 (the Summer). Her school homework was very little.
In Year 5, she did the same, but with more work during the Summer holidays between Year 5 and Year 6. She did quite a bit of VR and NVR and in the two weeks before Tiffin Round 1, she did lots of maths and MCQ English under timed conditions. For Tiffin Round 2, we focused on English because 60% of the marks are for that paper and her Maths was in excellent shape.
Over Christmas of Year 6, she worked 2 to 2.5 hours a day and spent the mornings skiing. I made sure she could do all the sample questions for LU and SPGS. For WHS, I knew she would be fine after her strong score on the Wandsworth test. For PHS, I assumed the prior prep for Tiffin and additional prep for SPGS and LU would help. For the Consortium, she did around 1 hour of prep on CEM style questions. She was already pretty good at those so we didn't do more of that. SPGS did not work out, but it helped with the rest.
It's important to be aware of your child's natural inclinations. Our DD picks up Maths very quickly and scores well on VR and NVR. She does not like comprehensions that much and her handwriting could do with
some improvement. I was not able to change her inherent tastes and aptitudes, but I was able to help her get to a reasonable level with Comprehension.