Did Ericsson study types of practice for beginners to good amateurs? The Cambridge Handbook of Expertise and Expert Performance (I believe this is your copy?) wouldn't cite that research. Ericsson's papers apparently all have to do with experts. There's one cross-performance-levels paper, about college students, which finds that studying in quiet environments and going to class help more than studying longer, which is consistent with deliberate practice models but also with many others.
I'm not sure he personally studied them, or just discussed the previous work. eg. from his '93 paper discussing the violinists:
...It is important to note that our study shows only that the amount and distribution of practice is related to the level of performance of adult musicians. In fact, many additional factors consistent with the skill-acquisition framework could attenuate the differences among our three groups. Sosniak (1985) found that international-level pianists had spent considerable efforts to seek out the very best musical teachers during their
http://www.codinghorror.com/blog/2008/08/quantity-always-trumps-quality.html
For some reason it just seems we in particular could learn something from this anecdote.
Iterate more. The practice effect is your friend as is mining out positive outliers in really huge sets. I wanted to also mention something about using going meta as a way to procrastinate but I feared I would summon a Newsome.
Edit: This has been mentioned before. I think it is good to remind people of it. Desrtopa writes:
It is therefore best to assume this is a parable.