The comment I'm referring to:
If I add 100 pounds to my squat, leg press, hip extension, leg ext and leg curl I'll be a better O lifter
Freaky deaky. First off, the skill level difference between the back squat and the clean is quite large, not to mention the snatch. Even so, building a big squat gives you a tad bit of slop to work with your technique, right?
But, leg press, hip extension, leg ext, and leg curl?
There's going to be a significant amount of integration to be done for those to improve any kind of real world movement. I could see hip extensions and leg curls done as part of an accessory regimen for a generalized leg strength program, but, would, in no way, expect them to do anything but strengthen a localized deficit.
It's best to start with integrated movements, and then, as you need, hit the localized deficits that will almost always occur at some point in time as you progress.