I feel that canned routines have their place and times, like anything here. I know this is really strange, but I think of this as a war. Use everything in your arsenal, and when you know you can't win, eject and find a new target.
Now when should you use canned material? I feel that canned material is great for openers. However, the most powerful openers are situationals, straight off the top. Of course don't stick on your openers...well they're just freaking openers. What I noticed about females is that even if it sounds kinda irrelevant or odd, as long as its interesting, you got em hooked.
What else are they good for? Not much else really, unless when you blank out. Like since the convo died fast, you might want to try some canned material. Sure they probably won't hurt, but you can't build a relationship off of that...and you're eventually gonna run outta **** if your game is ALL canned. That's what I learned, and I learned the hard way.
Oh, and one thing. Canned material is the best when you actually make it part of you. I can guarantee you, even though Mystery is so much more experienced than I am...after all I'm just some kid who didn't even get laid yet...my own routines work better than his. Why? Cause they're part of me. I can connect it with myself personally. I feel the emotion of my words. There is a certain power you can't imitate by parroting others.
All in all though...canned material works in clubs. Not very good in high school, but has its uses, like any other thing. And our goal is to eventually get your butt off those training wheels.