Buzz, I don't have any tricks to kick your progress up an Emeril notch or two....other than HGH. A few bits of advice from an old dude who's been there, done that.
First, forget worrying about bench and squat max. Straight bench press is not a good, pure muscle building movement and squats are hell on your knees and spine in the long run. And when's the last time you were walking down the beach and anyone asked you about your max bench press?
Second, if you read Muscle & Fitness or anything similar, enjoy the ads and
at the "Want to blast those biceps into oblivion" articles. Hey, this may be what I'm looking for to get those guns I've been trying for. Let's see:
3 sets of 10 reps/seated dumbell curls
3 sets of 10 reps/preacher curls
3 sets of 10 reps/standing barbell curls
WTF? I've been doing that for years. Wait, what's this fine print here? Hmmm.."3 cycles of Dianobol per month and 3 cycles of oil based Testosterone per month". Oooohhhh....now I see.
Bottom line. Without the assistance of PED's, the real keys to muscle growth or definition are diet and consistent change. You're right about "tricking" or shocking the muscles. But in order to do that, you need drastic, consistent changes. Adding a little something here or there will make very little noticeable difference. If you can get out of the mindset of worrying about how much...as opposed to how you look, change will come much easier. If you never have, go look at the "300" workout. (Just as one of many examples) It's an overall body workout using 25-50 reps on each exercise. You do far less sets but it's total exhaustion on each one and can be done in 30 minutes or less.
Virtually the entire cast was doing it in preparation for the movie. Go look at the promo pics and ask yourself if you want to look like that or if you want to increase your squat max by 20 pounds? Not saying you have to go to the 300 workout from here on. But for 4-6 weeks? Oh yeah. Then move on to something else to "shock" the muscles again. You were/are doing Insanity? Fantastic change of pace. Keep looking for overall routines to take it in another direction, but just as importantly, regardless of what you do, the results will be half of what they should be if you don't adjust the diet accordingly.