I agree with Whirlybird.
I am just finishing the ATPL NAVS with Bristol and am about to go for the 2 week brush up course. I gave up my job to study at home (supposedly full time) but have found my study patterns to be very erratic. I am not very good at spending long periods every day in the books, and instead just do what I can when ever I can. This means that some days I do loads, and on other days some times nothing at all.
I first completed the whole course, and then went back over it all a second time, finding that I understood lots of it far more easily the second time around. It can be surprising just how much you are learning without you realising it. I have a concentration span for study that is about as long a it takes to drink a cup of tea. Then, I get up, stare out of the window, walk around the house, and make another cup of tea - then hit the books again. I feel that I have been making the progress that I hoped for, but I will only truly know once the first exams have been taken.
Everyone is different. I know people that went on full time courses and spent 8 hours a day in the class room for 3 months, and still didn't really understand half of it. And, these people are not stupid in any way, but some people just have an ability to relate to the subjects, and therefore retain the information, and more importantly be able to apply it.
Personally, Climatology is my Nemesis. I'm fully prepared to have to sit that one more than once, but if that's the case so be it - it won't be the end of the world. Hopefully though the brush up course will help me get a better angle on it.
Good luck to all.....
Nish.