Whey Concentrate vs. Whey Isolate

ok so I've been taking both whey concentrate and whey isolate for a few months now, and I've noticed the helpfullness of both. But is there really a point to taking both types, and even a casein at night? I get the concept of the casein protein since its the slowest to digest and very beneficial for the several hours of sleep when your body is basically being starved, but what about taking both concentrate and isolate.

I've seen quite a few differant meal programs now that suggest only isolate, n some that suggest both. Wouldn't supplementing isolate protein every other meal, every few hours be just as good of an idea instead of using concentrate? I mean if I could walk in to the gnc n just buy one big ass tub of isolate whey n know that I'd be set for meals and post workout, then well I'd be set.
But does that work?

Don't sweat the small stuff. I wouldn't spend a fortune on isolate.