How people react is more important than the GTO EV differences. When playing 6max and you are on the BTN and there are two loose fish behind that is like proper limp type fish, you can just size your hand. They will be quite inelastic vs sizes and won't 3bet much. With two strong regs that constantly scan for tells and weaknesses, you need to hide as much information as possible so sizing based on hands is just asking for trouble. Most situations will fall in the middle. This idea applies to any spot be it preflop or postflop. On the river you can get away with more of this because it's much more difficult to get information about what you are doing, but don't be too obvious against observant players.

The GTO EV difference assumes perfect response and it will be super close compared to what is actually going on in a real poker game.

You always have a range of hands, and your overall range has an impact on the EV of all the hands that are in that range.

Which came first, the chicken or the egg?

The egg came first. The mother of the first chicken wasn't a chicken.

The ev's of different combos are related to the overall range. For ex, in which case does AA have higher ev?:
1. nit opening 4x utg or;
2. normal reg 2x raising utg?
Because the nit's range it tighter players will adjust and overall put less money in the pot which decreases the ev of the top of his range.

Shouldnt be the math for your example be like:

EV(range)=(EV(x)+EV(y))/2

Afaik: The EV of a range is just the Average EV of all included hands, right?
So i guess from a mathematical POV the answer to your question should be: no, it doesnt.

The fact the you are asking that question is a very good sign...and its quite an important one. From that alone, if you ever feel like a CFP is the right thing for you, let me know cuz I would be happy to have a talk with you ;)

That being said, it can easily be answered with a few toy games. You can just plug in some hands into a solver, then add/remove a few parts of the range and see what changes. From my experience coaching players over the years, the ones that "get their hands dirty" so to speak tend to develop quiker. So I recommend you do that. Come up with some simple enough scenarios that you can predict the output with simple calculations and then create some hypothesis for what will happen when you do X or Y. Then check it.

The answer to your question is a solid yes. The EV of a particular combo can certainly change after you introduce or remove certain hands in the range. But ultimately, the reason for that is simply that your opponent's counter strategy should change whenever your range changes. And if the opponent's counter strategy changes, then the EVs of individual combos will change. In certain specific situations, your opponent's counter strategy against specific parts of your range may not change after minor changes in your overall range, so its not going to happen for all hands at all times but certainly you can expect to see effects more often than not.

I could give plenty of simple examples that are easy enough to understand. Lets start with a river one.

You get to the river with AA (thats your whole range) and your opponent only has JJ, board is 222 33. The pot is P, stacks are 2P and you can bet any size you want. Thats kinda sad for your AA, cuz you simply dont have bluffing hands to make JJ indifferent. Every time you bet, JJ will pure fold. So here, the EV of AA is P (you just always take the full pot with a bet cuz JJ always folds).

Now lets imagine you introduce air hands in your range. Now you have sufficient hands to make JJ indifferent between call and fold. If you bet 2P, which is what the nuts should do in such a polarized scenario, then JJ will call you 33.33% of the time. So now the EV of AA is:

EV(AA) = 0.6666 * P + 0.3333 * (P + 2P) = 1.666P

So the EV of AA went up by 66.66% with the air addition.

As RaoulFlush said, the EV of your overall range is just the weighted average of the EVs of all combos in your range, so there is no much to it. In this quick example I said, the more air you add in your range, the less EV your overall range will have cuz all air has 0 EV.

If we transfer this to preflop, the logic is the same. If your opening range on the button for a given raise size is lets say exclusively 76s, then the blinds will play a lot of 3betting given how weak that range is. If suddenly you introduce AA in that range, the blinds wont be able to get away with nearly as much 3betting, so introducing AA in your range increased the realization and consequently EV of 76s.

This concept is quite important postflop, particularly OOP. Capped ranges will have a very hard time realizing equity because they cant bet into the pot and will face a lot of polarized bets. But as soon as you introduce nutted hands in your range, the EVs of those hands go up cuz your opponent's counter strategy can't deny equity to the weakest parts of your range anymore, otherwise it will get punished by your nuts.

Hope this helps

I am 2-3 weeks old to this forum/RIO ess member. This is the first time I am hearing this concept of EV of range not hand and I love it. Thank you GTO Warrior for the question and thank you all for the answers provided!!

In addition to the answers provided, Qing Yang has actually made a good video on this concept, based on an old twoplustwo post discussing something called "Shania". Recommend you check it out.