I think this is quite a misunderstood concept so I just felt like posting something on it. This should be quite simple and hopefully alot of ppl already understand it but i think should help and if nothing else hopefully it will decrease the "you have to have a balanced range" posts.
First point is that any sort of range balancing is only ever necessary vs. good thinking players. If villain does not think well at all about poker and is playing sub-optimally then you can play completely skewed and very exploitable because villain can't counteract your play. It does become important when players have the ability to 1. adjust and 2. read hands.
Second point is that there is a distinction between your actual
range at any moment and what villain perceives
your range to be at that moment. So say you just got caught running a big 3 street bluff and villain snapped you off really light. This indicates 2 things - 1. in order for villain to call you down light he clearly had to believe you had a high bluffing
freqency in the past and 2. he now has clear proof that you were bluffing and probably have been bluffing a fair amount previously. So now you clearly have to adjust your range to reflect how villain views you. So say 5 hands after this you run another 3 street hand. Now this is key - you want a very very polarized range here. In general, you should never be bluffing in this situation since your image is terrible and villain is just looking for any reason to call you. So your actual range is value (can be very thin, but is value nonetheless) but your perceived range in villain's eyes includes alot of bluffs, since he probably views you as an aggro donkey. The important thing is that villain knows we are capable of running a big bluff, even tho there are actually no bluffs in our range at that point given metagame considerations.
Now to merge these two points. When you have really good thinking players, they aren't going to see you bluffing once and then call you down light all day (if they are they are terrible). So in the above example, villain might very well lay down his hand coz he knows you know he saw your bluff and he knows it would be a terrible time for you to try to run a bluff given your image in his eyes and therefore you probably have something.
When we have a leveling situation like this, you then do have to shift the % bluffs % value part of your range or villain will catch on. So if we were to only start vbetting the top part of our range, our frequency goes way down and villain can pick up on our adjustment and readjust his range to play more optimally vs. our new range. And so we might have to keep value betting thin and bluffing some of the time, so villain isn't able to correctly adjust to our range (if we stop bluffing, villain can pretty easily take away alot of the pots for example). So even tho we take a loss on these bluffs when called, we make up for it in that villain fails to correctly adjust his range to the fact that most of our range is still very value-based. We want villain to make bad calls vs our overall range, but we still want him to be thinking we are bluffing more than we are so that he will continue to make these bad calls vs our range.
To summarize this entire paragraph - basically, we don't want villain's perceived range of us to match up with our actual range. But we don't want to polarize our range to the point that thinking players will pick up on it and readjust their perceived range to match our actual range.
Now again, for shitty players this doesn't matter at all. They'll see you bluffing and they just can't get that out of their head. So vs these players you can absolutely have the most skewed range on earth and they won't adjust because they caught you bluffing and therefore you are a crazy maniac who should be called down super light. So you just respond by going for thin value and they get absolutely owned coz they keep calling you down with complete trash.
Last thing i want to go through is essentially what is meant by range balancing. Lets use check/raising a flop cbet as an example since i think it illustrates it well.
You open villain flats. Say flop comes T56ss. You cbet with 9T and villain check raises. Now what range does this villain have when he c/r the flop? Does he always 3B TT+ pre (or do you have any reason to suspect otherwise)? Is he capable of raising any T other than maybe AT? How does he play his draws?
Vs. a player with a badly skewed range on this flop, his range might very well be limited to his value part of 2 sets, 56 + his semi bluff part of 45, 87 and flush draws + their total junk. Alot of players will just flat with Tx, but they will raise 100% of their draws. Depending on how loose villain is and the board texture, there might only be 2 combos of 56 (if he'd only play 56s and the 5 and 6 on board are different suits), and there are 6 combos of 55 and 66. There are more combos of 45 and 87 than these combined and there are also likely many flush draw combos as well (if he loves suited cards then it could be more than all the other parts of his range together). And then add the % of junk in his range. So vs this range 9T is almost the nuts. 9T is every bit as good as AA in this situation, since we know villain can't raise Tx and doesn't have TT+ in his preflop range. So there are many ways to play the hand after this knowledge; however, the fact that villain's range is so horribly polarized makes playing optimally vs. his range very very easy. And if villain does something like lead 100% of turns after c/ring, then he is going to get absolutely and completely owned.
So in order for villain to improve this he should maybe consider mixing up his preflop range (say flatting some TT hands instead of 3Bing), start to check/raise lighter (so maybe raise JT here for value) and stop raising 100% of his draws and instead c/c with some of them. This would then make it much harder for us to read his hand range.
And to try and tie all this together - your actual c/ring flop range will want to be skewed towards countering villain's perception of your c/ring flop range. So if you have been raising alot of flops and villain has started to either play back at you or call down (ie. villain has adjusted to the high % of bluffs in your c/ring range) then you will want to start to raise light (so you can raise 98 on a 278 board) but remove the bluffs and poor equity semi bluffs from your range. But again, vs a thinking player we can't just repolarize our range or villain can easily adapt. And so it becomes a constant state of readjusting and trying to stay one head of what villain is currently thinking of us.
Anyways, didn't end up as simple as i was planning but hopefully you get something out of it.