is preflop 2x 4bet size optimal?

I've read that a 4bet sized to be twice the 3bet is the norm and that it is a good size to balance your value hands with your bluff because when you're bluffing you can easily fold to another raise and you invite calls and induce bluffs from aggroes when you have a monster.

This 2x size with give villain pot odds somewhere near 3.2 to 1 so he needs 20% equity for a break even call. 66 has 19.5% vs AA While 87S Has 30%. So if villain was in position he can practically call with everything and try to realize his equity. Is that something that we want to happen?

It's true that with a effective 100bb stack villain doesn't have the implied odds to make good calls but none the less he can still take your stack making break even preflop calls.

It's even worst when the effective stack is 150bb+, giving villain good implied odds.

So what do you guys think? Is this sizing the best still? That we should keep this size for balance and chalk it up as variance when we get cracked or make the sizing bigger and bluff less? Or some other option?

just caught a mistake,
i had used the breakeven percentage for bluffs formula instead of the Required equity formula.
it turns out that villain needs 44% equity to call. So that makes a lot of hands very unprofitable to call.
But still, question still hold.

well, it's not like players can call any hand that they 3bet pre to a 4bet 2x. pot odds are not everything. You still have to play it postflop and often you have to pay more money to realize 100% of your equity, so calling every 2x 4bet would be pretty bad.

Personally I think 4bet 2x is bad because we don't 4bet only aces. We have bluffs hands there too, like for example low aces suited A2s-A5s. By making our 4bet to 2x we will often get too many calls and it won't be easy to play it postflop. I think best sizing of 4bets is like 2.20-2.50x. IP it's ok 2.2x, OOP 2.5x.

Yeah okay 2.2x and 2.5x might add a little more fold equity yet still small enough to not get us committed. I'm gonna do some math later to see what it actually look like.