Good that your are including the Sagreras Series in your studies. They are exceptional for self study, and are considered the finest series available to students.
Advance at the rate that is comfortable to you, but of course push yourself a little too!.
I have the bound version of the series 4-6, and have played a few studies everyday for 20 years. So one answer from me is that you could work on these studies for the rest of your life!
I echo this wholeheartedly. What I love about the Sagreras series is that, not only does he provide a student with a good technical grounding, but his exercises are really musical, in most cases beautiful, and a lot of fun to play! There is nothing worse than having to trudge through sterile studies; and there is simply no need to do so.
There is nothing wrong with working on other methods at the same time (Shearer, Noad, etc.); it all is of benefit. However, some would have you forego Sagreras altogether. My advice: don't listen to them. Life just would not be as interesting!