Hi, Joel

I recommend that you do OG problems as you work through a particular strategy guide. Of course, you should learn the concepts and techniques in a given chapter first, but you will also then need to ensure that you can apply the concepts / techniques to real questions, and you should do that right after learning those concepts / techniques.

True mastery also requires that you analyze questions after you do them (even the ones you get right!) to learn everything you possibly can. I tell my students to spend twice as long analyzing a question as they spent doing it in the first place.

By the time you're done analyzing a question, you should be able to tell yourself two things:
- how to recognize a question of this type if you see one again (note that you should not memorize that specific question - it is highly unlikely you will see the exact question - but, for many questions, you are likely to see questions with a similar structure or set up, though very different numbers or details)
- how you're going to approach a question of that type if you see it again

Also, FYI, you don't need to do all of the OG questions in a problem set as you study a chapter or book - in fact, you shouldn't do all of them at once, because you will want to save some for review later.

Hope this helps! Good luck!