Whenever you are 3 betting in cash games you need to know exactly why you are 3-betting. You need to be either 3-betting for value or 3-betting as a bluff. Your preflop 3-bet ranges do not need to be merged. They do however need to be somewhat balanced but balance will occur naturally between the amount of time you 3-bet for value and 3-bet as a bluff. Let us first clarify what is a bluff and value 3bet:
Your value and bluff 3-bet range will change depending on position and players you are dealing with where your value range will increase/decrease and bluff range will increase/decrease depending on a variety of factors. For example, When you are out of position your value range should be larger then your bluff range. Also, the wider your opponents range the wider your value range should be. For example, you should be felting wider small blind vs big blinds, button vs blinds, cut-off vs button compared to say under the gun vs middle position.
Your bluff range should be based on:
Also, sometimes you will make a profit because a villan will call and check-fold whenever he misses. So you are essentially just building a pot to bluff. You can also make a profit when he is the type of player to peel flops light and fold to lots of turn bets. You need to do your work and catagorize the player to figure out if he is this type.
Your bluff range should be made out of the best hands that aren’t good enough to flat preflop, and arent in your value get it in range. So these could be 75s, 45s, 56o, q7s, j4s Tjo Qjo etc etc. Frequently hands like 89s, Tjs, Qjs, KQo are good enough to flat preflop so those should not be 3-bet. Hands which are tweeners like AQ, 99 can be 3-bet but before you do it you have to know exactly how you are going to react to a 4-bet. If it is someone who will call wide you can 3-bet these hands and your value will come from playing postflop, even though they are strong hands you can comfortably fold when 4-bet.
Against people with a wide playback range you don’t want to 3-bet as a bluff because they will call you wide and you will frequently be inflating the pot with a weak hand against someone who will playback against you preflop or postflop. Against people with a small playback range you want to 3bet them with all sorts of hands as a bluff because your initial preflop 3bet will be much more effective.
Against fish you can merge your range by taking out your bluff hands and putting in hands like AJ KQ QJ AT AQ. Pretty much any double broadway hand. The reason you can do this is because: 1) They will playback with such a wide range you can be happy getting in your top pair with AJ or KQ on the flop because they will be calling so many dominated hands. He will also play fairly fit or fold on the flop and check fold when he misses and call down lightly when he gets a small piece. 2) They will not be good at 4-betting, so if you get 4-bet you can comfortably fold. 3) You are isolating him so you play more pots with him and the other regulars at the table cant.
EDIT: My philosophy has changed slightly since writing this post. What I now believe is correct, or I didn’t outline when I wrote this post, was that I think you should polarize when your in position and merge when your out of position. What I mean by this is when you are in the blinds vs a late position opener, you should merge your range to include hands like KQ AQ AJ whereas I would frequently flat them in position. The primary reason for this is because the late position openers will flat incorrectly with a wide range. Just think of it like this, if your opponent is always calling from late position to your BB 3-bet with TJs and JQs, you should be 3-betting hands like KQ and AJ and try to stack your opponents when you flop top pair. Wheras, if I am the BTN and 3-bet there CO open they are less likely to call out of position with TJs and QJs type hands.
I hope this cleared a few things up. Good luck at the tables!