It's all in the Continuing Range!

A HUGE subject that I've come across in research over and over again is continuing ranges (I think I've heard them called continuance ranges too). Especially recently, this concept has been aired time and time again, and I've only just come to realise it's importance.
For those among you who may be unaware, I'll try and explain the concepts' significance in the next paragraph.
A continuing range is the range of hands that your opponent will continue with after you bet or raise. Hands that we raise for value in any situation should have good equity against an opponents' continuing range. If we bluff, we should pick hands that are too weak to call (given pot odds) but whose equity isn't terrible. It is currently considered optimal to raise gutshots, overcards, back door draws and combinations of these and other weak draws when we bluff on the flop. This is because they typically have around 25% equity with two cards to come.
When one bets or raises, according to the standard risk reward equation a bet can often (in NLHE) be profitable no matter what the cards are if villain folds too much. In this situation we should often be bluffing. When we do bluff however, we can improve our expected value on the play by picking the best hands to do it with. What we need is for our hands to have decent equity when we are called. Here's a common example: MP (solid reg) opens and we have AJo on the button. 3-betting here is usually going to show a positive expected value, so why not? Because when villain continues there are not many hands that we beat up on and our equity is generally poor. AJo is good enough to play, so call and 3-bet something that is a more marginal call but will play decently post flop - T9s?
Anyway the purpose of this post is not to cover tons of situations, but just to make anyone who isn't already aware of the concept that it exists and that it is worth further research. GL!