Hi Dan,
If advance routine is not either a) a viable keyword structure, or b) a logical hierarchy structure, then I see no reason on having it. If however, it is a keyword used for a logical category structure then you should.
Now looking at your site, I see little reason to change the structure.
http://spytunes.com/practice-guitar/beginner-routine/what-is-the-s-e-p-r
This URL string makes sense and is only three deep. Which pages are not doing well for you?
As far as indexing, your most important pages should be two clicks from the home page (recently discussed in the WBF).
Although moving them one step up will not hurt as long as you remember to 301 the pages as to not spill the link juice.
If a particular page is weak, then start building links to that page. Such as linking to those pages from blog post, tweets, facebook post, and other external link building.
I hope that helps