I'll echo Brent, the time each section takes really depends on your current level. I'm pretty much learning everything again from scratch and it takes me on avg 30mins-1hr for each chapter(I'm using MGMAT), not including the accompanying OG Guide problem sets. Sor far it's taken me 14 real days to reach "Day 10" in the study guide (but honestly, a few of the days I've only put in <2hrs). I should also note that my intention has always been to devote 90 days to prep, so my purposes for using this guide is solely for it's structure and content.

My plan is to continue to plug along and catch up on the lighter days(ex: Day 11 only covers one chapter and just 11 problems in the OG Guide!). And again, as Brent mentioned, the last few weeks are really just devoted to practicing and working on weaknesses.

And to answer your question directly, I do feel as if the 60 Day schedule is working and has helped me so far. I've been thinking about getting my MBA for well over a year now, and have attempted to power through the materials on my own. But after two unsuccessful starts, this is the furthest I've gotten in the materials. I hope I can keep it up!

So my advice would be to just hang in there, do as much as you realistically can each day and use lighter days to catch up on anything you might not fully grasp.

Hope all this helps!
-Herbert