In contrast we're not doing "papers" at all at the moment - much like Daogroupie's approach we're just doing some chosen questions which are of the types he sometimes gets wrong, or any I can dig up which are presented in an ususual way for maths and NVR, and mostly work on comprehension/cloze, and more generic vocabulary (but freerice, random dipping into a thesaurus, etc, not papers). Sometimes for maths I don't even get him to answer the questions, just to talk through what the method he would use is - if he can convert from a worded question to what the calculation should be correctly, we don't actually need to practice doing the calculation.
I doubt we've been averaging more than 30 minutes a day in total. But I guess it depends upon the child - If I tried to get mine to do 5 papers a day he'd just down tools completely and refuse to co-operate (which he does sometimes even with the limited amount we are doing!).
Agree that it's feedback and focussing on areas for improvement which are most important. We're definately spending longer on discussing what he's done or on the methods than on the actual doing - particularly on the more subjective areas like comprehension. I am cobbling together a couple of "papers" which mimic the CEM format of having multiple timed sections, and not being able to go back to earlier sections though, so that we can do one or two trial runs of the format, and get used to doing the two "papers" with only a small break in the middle.
At the end of the day if it is going to take at least 5 hours of work a day (maybe more if they're going over the papers too), during the school holidays, to get in, then you could be looking at that level of commitment for the next 7 years. If that's the case then it's probably not the right place for them, and I'd settle for the alternative (although we're lucky in that we do have a good alternative available to us). Yes ideally I want him to get a place - but I want him to have the opportunity to enjoy his life for the next 7 years too, which means more than just working non stop. And other schools can and do get good results too if the kids are capable of it.