When I first got into picking after trolling through threads on here decided not to rake anything and SPP only and I think it was sage advice from those who provided it (thanks to those who said that by the way). Only after nearly a year of picking did I really start trying to rake anything and only after I couldn't pick it open. What I found true (for me anyways) is that I can't effectively rake open anything with serrated pins, or any security pin really for that matter and locks that give me a fit picking generally will rake open pretty fast or set enough pins that a diamond pick passing over the stack will get the last one or two and open the lock.
On the other side of that I have a buddy who rakes first and asks questions later and is pretty successful with this method. I have seen him rake open locks that neither of us thought could be raked and then he couldn't turn around and SPP it, but could rake it every time in about the same amount of effort.