I'm playing a 3-bet or fold strategy in the SB as that is the strategy I have seen recommended on RIO and other sites. I am wondering if it is worth considering building a flatting range in some situations. The issue I have with playing 3-bet or fold is that I feel I almost put myself into a cage where when I 3-bet, I'm getting to the flop with a very obvious range of pocket pairs and broadways. This can be easily exploited by villains who can call 3-bets in position with a lot of hands (especially when they are in UTG/MP and have a strong opening range to start with). On a lot of flops, they will have the nut advantage. On low and middling flops, the IP caller will have more sets and two pair combos, and they can also have more straights on connected flops, and flopped flushes on mono flop. They will also have more FD combos and two-tone flops as they can call IP with stuff like QJs, T9s, A5s that I'm not 3-betting in the SB. I have been thinking of trying to play a less linear and more polar 3-bet range in the SB, similar to the BB 3-bet range.
Also, is it best to never have flatting range in the SB even if you are deepstacked with the opener? I understand that you are supposed to 3-bet less often in any position when you are OOP and deep with the opener, and the IP player is incentivized to call much wider when facing a 3-bet when deep (as positional advantage skyrockets into orbit as stacks get deeper), which would seem to incentivize calling more in the SB in some spots.